I have two exercises for people who may not be able to move around easily or has knee troubles. Water aerobics and Chair aerobics. You might not think you could get a workout doing either but I'm here to tell you it's possible, especially the chair aerobics. I have had both of my knees replaced but I still have to watch the impact on my knees (no running or jumping). My surgeon actually wants me to stick with the chair aerobics. It's all about the intensity you put into it.

Some of the things I do in my office - I keep a set of grippers, a small 5 lb ball and a set of 3 lb dumbells under my desk. While reading emails, I will use the gripper 10 squeezes then switch hands. The doublebells can be used for basic curls or arm lifts. I use the ball more for stretching and toning. Put it in your left hand, hand down by side. Slowly raise it over your head as you stretch, switch to the right hand at the top then slowly lower. Repeat going opposite direction. It works a quick pick me up for energy. You can also doing going forward and backward around your waist. Adding a twist helps even more.

If you want to work you lower body, you can put ankle weights on and do leg lifts under your desk, or put the above mentioned ball beween your feet/ankles/calf and do leg lifts.