If you cannot do any excersize (ie - can't leave the office) I found the Tibetan Rites to be a very good alternative to jogging/cycling. At least you are doing something.

Since I started doing to tibetan rites I manage to work longer without needing a break, and manage to keep to deadlines more (but yea, still miss them). Apparently helps getting the entire energy system flowing which in turn leaves you energised and refreshed.

More info here:

http://www.lifeevents.org/5-tibetans-energy-rejuvenation-exe...