Some baby boomers are still very active and youthful (the first helps maintain the second). But whether you spend much of your day in a chair or on a couch, or whether you spend it being youthfully active, don't waste the opportunity of getting an easy workout just because you're sitting down.
You can still strengthen your body and make it more flexible while sitting. As a boomer, anything that helps maintain your strength and flexibility will prolong your functionality and make your life more comfortable.
Start with the easiest exercise: leg lifts. Lift one foot until that leg is straight out in front of you, put that foot back on the floor and lift the other leg. Do this 20 times on each leg about five times a day. It will help develop leg strength as well as synovial fluid, the lubricating substance of the knee.
If you feel a slight pull in your upper calf and the back of the lower thigh during leg lifts, it means you've lost a lot of flexibility, and need to do some stretching; specifically toe touches. You can do these sitting or standing; they're pretty easy. With your leg straight, bend from the hips and reach to touch your toes. If you can't touch your toes, extend your reach by putting a towel behind the ball of your foot and pulling on both sides of the towel.
If you're active and in shape, you can add to the strength-building quality of leg lifts by wearing a pair of ankle weights while you do them. The adjustable weight kind are best. Start with two pounds, and add one pound a week. This will help build even more strength in your thighs. Stash the weights under the couch so it's easy to grab them when you sit down to watch TV.
If you have no problems with back pain, try some back-strengthening exercises. Start with simple floor touches. While keeping your back as straight as possible, sit on the edge of your seat, bend at the hips, lay your upper body over your thighs and reach down to touch the floor. Then sit up straight. Those already in good shape may wish to use a pair of lightweight dumbbells, reaching down to pick them up. This will strengthen the abs as well as the spinal erectors, thick columns of muscle that help support your upper body.
Use a 5- to 10-pound pair of dumbbells to do biceps curls and work your arms while watching your favorite TV show.
Sit up straight, so that your back isn't resting against any support. Hold a dumbbell in each hand beside the outside of the knee. Alternate bending each arm up to the ear, and clench your biceps as you do. This will tone and strengthen your upper arms so they won't have the flabbiness that often comes with age.
The obliques, the muscles on the sides of your rib cage and abdomen, are important for balance. Since falls are one of the biggest sources of injury for people past 50, it's good to strengthen these often neglected muscles, and it's a simple exercise to do while sitting. Hold the dumbbells on your shoulders and slowly twist your upper body from side to side. You can also do this without weights, but a little resistance works the obliques more efficiently.
If you want to eliminate "batwings," loose and flabby skin at the back of the arms, hold the dumbbell at ear height and slowly lower it until your arm is straight. This will build and strengthen the triceps muscles in the back of the arms.
Make it a habit to work your body while sitting. You can make TV-watching a productive experience that will help you stay in shape, and best of all, keep your body more youthful for the rest of your life.