OPINION OF THE COURT
Paulette Griffin seeks review of the Social Security Commissioner’s final determination denying her concurrent applications for disability insurance benefits and disabled widow’s benefits under Title II of the Social Security Act, 42 U.S.C. § 423, as well as supplemental security income under Title XVI, 42 U.S.C. § 1381a. Griffin’s applications were denied at all administrative levels, including an administrative hearing. The District Court affirmed the Commissioner’s final determination that Griffin retained the residual functional capacity to perform light work, including her past relevant work, and therefore was not entitled to disability benefits. On appeal, Griffin argues that the Commissioner’s determination is unsupported by substantial evidence. We exercise jurisdiction pursuant to 28 U.S.C. § 1291. Finding that substantial evidence supports the Commissioner’s determination, we will affirm.
I. Background
As we write for the benefit of the parties alone, we include only those facts necessary for disposition of this appeal. On March 24, 2004, Paulette Griffin filed concurrent applications for social security disability benefits, noting an inability to work since February 20, 2004. On February 24, 2004, Griffin was admitted to the Albert Einstein Medical Center for chest pain following cocaine use. After cardiac catheterization revealed multi-vessel disease, doctors performed a coronary bypass. For six years preceding her heart surgery, Griffin worked as a night auditor at a Best Western Hotel. There, Griffin answered the telephone, checked guests in and out of the hotel, and prepared reports of daily receipts. According to Griffin, the job required approximately eight hours of walking and standing, one hour of sitting, and lifting reams of computer paper weighing less than ten pounds.
The Social Security Act grants disability benefits only to those claimants who demonstrate an “inability to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or which has lasted or can be expected to last for a period of not less than 12 months.” 42 U.S.C. §§ 423(d)(1)(A); 1382c(a)(3)(A). The Pennsylvania Bureau of Disability denied Griffin’s application for benefits, finding that Griffin’s medical conditions did not render her incapable of returning to her past work as a night auditor. Griffin requested review of her applications at an administrative hearing before an administrative law judge (ALJ), and supplemented the administrative record with additional medical evidence. The ALJ, considering Griffin’s testimony at the hearing as well as all medical evidence in the record, found that Griffin possessed the residual functional capacity to perform light work, including her past relevant work as an auditor and bookkeeper. In accordance with this finding, the ALJ concluded that Griffin was not disabled and thus ineligible for disability benefits. See 20 C.F.R. §§ 404.1520(a)(4)(iv), 416.920(a)(4)(iv). The Appeals Council denied Griffin’s appeal, rendering the ALJ’s findings and *888conclusions the final determination of the Social Security Commissioner. See 20 C.F.R. §§ 404.981, 416.1481. The District Court, reviewing pursuant to 42 U.S.C. § 405(g), affirmed.
II. Discussion
Congress has provided that our review of the Commissioner’s determination of disability benefits is for substantial evidence. 42 U.S.C. § 405(g). If supported by substantial evidence in the record, we are bound by the ALJ’s findings of fact. Plummer v. Apfel, 186 F.3d 422, 427 (3d Cir.1999). Substantial evidence is “more than a mere scintilla. It means such relevant evidence as a reasonable mind might accept as adequate.” Id. (citing Ventura v. Shalala, 55 F.3d 900, 901 (3d Cir.1995)). The ALJ’s conclusion that she retains the residual functional capacity for light work, according to Griffin, is unsupported by substantial evidence.
In her applications for disability benefits, Griffin identified her heart attack as a medical impairment limiting her ability to work. Griffin further indicated that this heart condition limits her ability to stand for “any length of time” and prevents her from bending down or lifting anything over ten pounds. (App.63.) Griffin also noted that she has difficulty ascending stairs, and must rest her legs after sitting for a prolonged period of time. (App.85.) The ALJ considered these claims, noting that Griffin’s “medically determinable impairments could reasonably be expected to produce the alleged symptoms.” (App.24.) Rather than base the disability determination solely upon Griffin’s heart condition, however, the ALJ properly assessed the specific question of whether her medical impairment imposed functional limitations that precluded her employment as an auditor and bookkeeper. See 20 C.F.R. §§ 404.1520(f), 416.920(f) (“Your impairments) must prevent you from doing your past relevant work.”); see also Coria v. Heckler, 750 F.2d 245, 247 (3d Cir.1984) (“[T]he fact that a claimant suffers from a physical impairment does not prove that she is disabled. Disability is present only when the functional limitations imposed by the impairments are so severe as to prevent all substantial gainful activity.”). As to this inquiry, the claimant bears the burden of proof.1 See Adorno v. Shalala, 40 F.3d 43, 46 (3d Cir.1994).
On the issue of functional limitations precluding her ability to work, we find, as the ALJ did, that Griffin’s proffered evidence is sparse. At the administrative hearing, Griffin testified that memory deficiencies, leg fatigue, and sensitivity to stress preclude her employment as an auditor and bookkeeper.2 Substantial evi*889dence sustains the ALJ’s rejection of these limitations.
A. Memory Loss and Leg Fatigue
As to memory loss and leg fatigue, the ALJ properly concluded that these conditions did not limit Griffin’s ability to perform her past relevant work as an auditor and bookkeeper. As an initial matter, Griffin’s memory loss and leg fatigue were not substantiated by medical evidence. Although Griffin complained of headaches and hip and shoulder pain in physical examinations following her surgery, she failed to inform the physicians of any condition involving her legs or memory. (App.290, 292-94.) Further, even if Griffin did experience leg discomfort and memory loss, there is no medical evidence that either condition limited her ability to work as an auditor and bookkeeper. Griffin proffered no medical evidence, for example, that her leg fatigue signals an unsafe cardiac condition; instead, she simply testified that her legs “get tired” because she does not have the strength that she “used to.”3 (App.830.) The ALJ properly concluded that mere fatigue — without more— does not preclude Griffin’s employment. Indeed, Griffin adduced no evidence — other than her own testimony — indicating that her leg pain was sufficiently severe to preclude her performing sedentary tasks, including her past relevant work as an auditor and bookkeeper. In any event, the ALJ concluded that Griffin’s testimony, unsupported by medical evidence, was not entitled to great weight.4 (App.24.)
Griffin’s other asserted impairment— poor memory — was also properly rejected by the ALJ. In particular, Griffin proffered no medical evidence that bookkeeping or auditing requires high memory function, or that her memory skills would be inadequate for the job. On this sparse record, the ALJ reasonably concluded that *890Griffin could resume work as a bookkeeper and auditor.
B. Sensitivity to Stress
We also find that the ALJ properly rejected Griffin’s contention that sensitivity to stress precluded her employment as an auditor and bookkeeper. At the administrative hearing, Griffin did not elaborate the nature of her impairment, which could stem from a psychiatric illness or an underlying cardiac condition. The ALJ, which found no evidence of a psychiatric condition, properly rejected the former rationale. As to Griffin’s heart condition, the ALJ weighed the medical evidence in the record, including the opinion of Dr. Frank James, Griffin’s treating cardiologist, and Dr. Oliver Finch, the state agency physician, and concluded that Griffin’s heart condition did not prevent her from returning to her past work. Substantial evidence supports the ALJ’s conclusion.
Griffin had undergone a successful cardiac catheterization and coronary artery bypass graft, after which Griffin had not expressed any cardiac complaints. As Griffin recovered from the surgery, cardiovascular stress testing in July 2004 displayed defects in the inferolateral and lateral wall regions, suggesting scarring and constricted blood supply. (App.22, 284.) Nonetheless, check-ups conducted by Dr. James in April and May of 2004 revealed a normal heart rate, normal blood pressure when sitting or standing, and no recurrent angina. (App.23, 236-38.) These results were consistent with Griffin’s cardiovascular exam in April of 2004, which, with the exception of a slight systolic ejection murmur, was normal. (App.23, 237.) Dr. Matthew Rusk likewise found no evidence of acute distress in his examination of Griffin in September of 2004. (App.292-96.) An ultrasound performed by Dr. Fairman, a vascular surgeon, in September of 2004 looked “fine,” and Griffin was informed that she had no need for another examination until the following year. (App.23, 292-93.) After reviewing this and other medical evidence, Dr. Oliver Finch concluded that Griffin could perform light work, including bookkeeping and auditing.5 (App.272-79.)
For her contention that she is incapable of performing her duties as a bookkeeper, Griffin relies heavily on Dr. James’s opinion. On Griffin’s employability assessment form, Dr. James noted that Griffin was “temporarily disabled.” (App.114-15.) In an April 2004 letter to Dr. Rusk, Dr. James stated that Griffin “has been unable to work” because of her medical disability. (App.236.) In assessing whether Griffin retained the residual functional capacity return to her past relevant work, the ALJ carefully weighed — and rejected — Dr. James’s opinion. First, Dr. James failed to explain why Griffin’s prior operation precluded performance of sedentary tasks. Instead, Dr. James simply completed a
*891check-list form concerning employability for the Department of Public Welfare. See Mason v. Shalala, 994 F.2d 1058, 1065 (3d Cir.1993) (“Form reports in which a physician’s obligation is only to check a box or fill in a blank are weak evidence at best.”).6 Second, Dr. James’s letter to Dr. Rusk also failed to identify any specific functional limitations imposed by Griffin’s cardiac condition. Third, and most important for the present analysis, neither James’s letter nor the employability assessment form directed Griffin to avoid stress, identified exposure to stress as hazardous to Griffin’s health, or indicated that bookkeeping would entail harmful levels of stress.
Despite this, Griffin insists that deference to Dr. James’s opinion is obligatory. We disagree. The determination of disability is a conclusion of law for the Commissioner; a physician’s statement that a claimant is “ ‘disabled’ or ‘unable to work’ does not mean that we will determine that [the claimant] is disabled.” 20 C.F.R. § 404.1527(e)(1). A treating physician’s opinion is only controlling when it is “well-supported by medically acceptable clinical and laboratory diagnostic techniques, and is not inconsistent with the other substantial evidence in [claimant’s] record.” 20 C.F.R. § 404.1527(d)(2). Where, as here, the treating physician’s opinion is conclusory, lacking explanation, and inconsistent with other medical evidence in the record, the ALJ may choose not to defer to the opinion. See Jones v. Sullivan, 954 F.2d 125, 129 (3d Cir.1991).
Here, the ALJ reasonably determined that Dr. James’s opinion was inconsistent with other substantial medical evidence in the record. As an initial matter, Dr. James’s conclusion was inconsistent with his own treatment notes, which confirmed Griffin’s improved, post-operative cardiac function, and inconsistent with other medical evidence in the record, which indicated that Griffin’s heart rate and blood pressure were normal. Further, imaging techniques did not reveal an enlarged heart, which would have limited Griffin’s ability to exert herself physically. Finally, as part of the evidence inconsistent with Dr. James’s opinion, the ALJ considered an assessment completed by Dr. Finch, which, unlike that of Dr. James, addressed the issue of functional limitations. After reviewing the medical evidence in the record, Dr. Finch concluded that Griffin retained the capacity to perform “light work.”7 (App.272-77.) Thus, given this substantial *892evidence indicating that Griffin retained the capacity for light work such as bookkeeping, the ALJ did not err in declining to assign controlling weight to Dr. James’s opinion.8
Accordingly, we conclude that substantial evidence in the record supports the ALJ’s conclusion that Griffin retains the functional capacity to return to her past relevant work.
III. Conclusion
For the foregoing reasons, we will AFFIRM the Order of the District Court.