The psychological benefits of walking and jogging were compared in 52 symptomatic neurotics over an 8-week training period and subsequent 6-month follow-up. Both groups showed marked reduction of anxiety, depression and global symptoms. Joggers had greater aerobic gain, but no greater psychologic benefit. Significantly larger numbers of joggers dropped out of the study. There was no relationship between aerobic gain and reduction of symptoms at the end of the program. However, at 6 months' follow-up, those with greater aerobic fitness had much lower anxiety levels. Changes in exercise frequency and aerobic capacity were also maintained at follow-up. Depression levels were not associated with aerobic fitness at follow-up. High initial exercise intensity appears to inhibit the forming of new exercise habits.