Our understanding of the concept of purpose, derived from our experience as purposeful beings, requires some ultimate purpose at the end of a chain of purposes. Often, of course, a person is motivated by several simultaneous purposes, and occasionally these may overlap in such a manner as to give the superficial appearance of circularity or infinite regress. A distance runner may train in part in order to prepare for races; she may also participate in races in order to increase her motivation to undergo long, grueling hours of training. In this instance, her training and her competitive efforts both no doubt serve a combination of several ultimate ends, including both psychological and physical benefits.