We are humans and not designed to work for hours on end without rest. If you want to stay optimally productive use Casey’s eTip: Take Micro-Breaks During the Day.
A study by the University of Connecticut found that four short relaxation sessions (e.g., 1.5 – 2 minutes) throughout the work day provide the same stress reduction as 15 minutes of progressive muscle relaxation. Just “relax, breathe slowly and deeply; and imagine a peaceful, serene place.” If you think you don’t have 90 seconds, it’s time to stop and take stock. You’ve lost perspective.
Source: (Prevention magazine, May 2009)