Carry hand weights to work
Place a pair of hand weights in your desk drawer. Bring them out a few times a day and spend five minutes doing biceps and triceps toning exercises. You may want to shut the office door before you do this unless you enjoy having people laugh at you.
Take a lunchtime fitness walk
Instead of heading down to the cafeteria to eat a 500 calorie meal, bring a high protein, low calorie fitness bar with you to work. While everyone else is packing on the pounds in the lunch room, take a brisk, thirty minute fitness walk outdoors. Watch the pounds fall off.
Stop being so efficient
Spend more time walking around the building. Why make only one trip when you can turn it into two or three and burn more calories at the same time? Take a five minute walk around your office several times a day. Park as far from the front door as you can in the morning.
Wear a pedometer
Studies have shown that people who wear pedometers burn more calories during the day. Strap one on in the morning and make it your goal to walk at least 10,000 steps before hitting the bed at night.
Join a nearby health club
Join a health club right around your office and go there at lunch. Not only will it help you get into shape, it'll make your more mentally alert so you'll get your work done faster.
Do stretching exercises
Find a book that shows you how to do stretching exercises. Find ones you can do unobtrusively in your office. Do them several times a day. This also helps to break the monotony and restore your mental alertness.
When you leave work in the afternoon, you'll be content knowing you didn't sit in front of a computer all day. Plus, you'll have more energy to enjoy the evening.