Researchers at the University of Texas, investigating the link between exercise and depression, have found that thirty minutes of brisk walking lifts the mood of sufferers, giving them a greater sense of vigour and improved psychological well-being for up to an hour afterwards. Forty subjects aged 18 to 55 were referred to the study after diagnosis of major depressive disorder. Twenty were assigned to treadmill walking while the remainder were assigned to a quiet rest control group.
(Effects of Acute Exercise on Mood and Well-Being in Patients with Major Depressive Disorder. Medicine & Science in Sports & Exercise, December 2005.)