Sitting around working on your desk for endless hours at a time can cause more harm than good. Sitting still makes your heart rate and blood circulation slow down as your brain relates the stillness to sleeping. It also weakens your muscles thus making it harder to do physical tasks.
Exercise for a least half an hour every day, be it at the gym, at home, dancing, jogging, etc. If you don’t have the time, then try walking around every hour at your workplace.