As defined in the Americans with Disabilities Amendments Act of 2008, the Americans with Disabilities Act of 1990 and Section 504 of the Rehabilitation Act of 1973, a disability is a mental or physical impairment that materially restricts one or more major life activities. If there exists a mental or physical condition, a history of such a condition, or a condition that may be considered by others as substantially limiting, then you may have a legally defined disability.