Regularly scheduled work breaks are important for concentration and productivity
Ever since I was a Naturopathic student (20+ yrs ago) I decided I would schedule a gym break in the middle of my long clinic days (Tuesdays and Thursdays) to break up these 10-12 hour days. It helps me to refocus and provide better care for my patients. Now this idea is backed up by CMHA in Toronto. You can listen the CBC podcast interview for more on this idea and work breaks into your day.