Heading to your office gym or fitness club to do at least 20 minutes of cardio a few days a week: the elliptical, treadmill, rowing machine, stair master, pool, power plate, or any other form of cardio are all excellent options for getting your workouts done (what you choose to do should depend on your individual condition, body type, and goals).
FORBES: NYC Psychiatrist and Hemingway On The Benefits Of Exercise On Work And Depression