Reference:
Chalder M, Wiles NJ, Campbell J, Hollinghurst SP, Haase AM, Taylor AH, Fox KR, Costelloe C, Searle A, Baxter H, Winder R, Wright C, Turner KM, Calnan M, Lawlor DA, Peters TJ, Sharp DJ, Montgomery AA, Lewis G. Facilitated physical activity as a treatment for depressed adults: randomised controlled trial. British Medical Journal 2012;344: e2758.