The types and frequency of sensations experienced by runners when required to miss a run or series of runs was studied. Most of 345 runners of various weekly mileage levels reported some kind of distress; irritability, restlessness, frustration, guilt, and depression were reported most often. Sleeping problems, digestive difficulties, and muscle tension and soreness were reported less frequently. Three causes of exercise withdrawal were proposed: (a) a misinterpretation of the return of dysphoria that had been temporarily masked by the effects of running; (b) an inability to cope with stress in periods when the coping mechanism of running is temporarily unavailable; and (c) the loss of regular, predictable reinforcement of feelings of self-fulfillment gained through success or achievement in previously unimagined and unattainable ways. Results, based on cross-sectional data, were consistent with these hypotheses but do not rule out alternative explanations. The reciprocal nature of number of miles run in an average week and exercise deprivation sensations was also studied. Results indicated that runners tended to run longer in order to avoid the negative sensations that would come from not running, but that an escalation in mileage did not necessarily result in more frequent experiences of distress when not able to run.