A study published in the July 2014 Mayo Clinic Proceedings, has evidence suggesting that sitting for two hours negates 20 minutes of exercise done that day. The average American sits for over 7 hours per day. You would need to exercise for over an hour and a half every day to negate the harmful effects that sitting has on your body.
One was to reverse this is to do a one minute break every 30-60 minutes.
Forward Seated Punches
With the arms slightly below shoulder level, alternate the right and left arms and jab them forward. Thrust forward quickly with your arms as fast as you can. Do not lock your elbows or fully extend your elbow joint.
See these and other seated breaks in Chapter 10 of my book, Health at Your Desk.