Well, I could tell you about people like Kelly Nelson and Morjoie Newlin, two female bodybuilders. They're not your typical bodybuilders. Kelly Nelson first began training with weights in the early 1980's at age 53 and was still competing in the 21st century in her late 70's...in a bikini...and lookin' good if I may say so!
Morjorie Newlin was in HER 70's before a 50 pound bag of cat litter convinced her that if she didn't do something, old age was going to be a difficult time. That's when she began a fitness training program that included weightlifting. Morjorie Newlin was participating in bodybuilding competitions, and winning, in her 80's!
Same comment...in a bikini and lookin' good.

Now, obviously, these are special ladies who put in a lot of extra effort to accomplish some specific goals, but it does make a point. Life...and fitness...does not have to end at 40. Both of these ladies STARTED their fitness careers after age 40. Kelly Nelson was 53 and Morjorie Newlin was 72.
Years later, both were still active in their chosen fitness areas and still enjoying life as well as, or better than, many in their 30's or 40's.

Fitness over 40? Heck, all around the globe, people in their 80's are skiing, hiking, canoeing, biking. Some, not so adventurous, are lifting weights or sweatin' along with Richard Simmons. Some are black belts in Karate, and some quietly and calmly practice yoga or tai-chi.

As easy as this sounds, fitness over 40 requires regular performance of the proper exercises. Just as in our 30's or 40's, sitting in the easy chair, clicking the remote, doing 16 ounce curls with a Miller Lite just doesn't cut it. However, it is not necessary to pack up and head for the gym and try to keep up with the hardbody cuties, either.

It IS necessary to pick an exercise program or physical activity, combine that with some healthy eating habits...AND STICK TO IT!

Even over 40, the benefits normally associated with a regular, moderate exercise program will kick in, but for seniors, some benefits are of special importance.

People over 40 tend to break bones, usually from falling.

As we age, bones weaken, as do muscles. We lose some of our proprioception, the perception of stimuli relating to a person's own position, posture, equilibrium, or internal condition. Our ability to react quickly to a loss of balance, whatever the source, or to avoid an obstacle or actual peril becomes diminished.

Exercise helps bones stay strong and exercises such as weightlifting and other resistance training help your body maintain balance and stability. Weight bearing and resistance exercises assist the body in maintaining proprioception by improving the connections and conditions of the muscles and their anchoring in bone.

This training also triggers the reconditioning of the signaling system from body to brain which allows the brain to realize the danger and transmit the appropriate signals to muscles which can react to correct the situation. Weightlifting and resistance exercises can help give your muscles the strength and agility to respond to those signals if you are tripped, off balance, or in other peril requiring quick reaction.

People over 40 begin to lose their zest for living and experience more health crises.

Part of this is due to normal changes that take place as we grow older. Our bodies get thicker and lose the gracefulness of youth. Things seem to become heavier and harder to move, and we begin to feel aches and pains that often accompany aging. Some of those aches and pains may be due to arthritis, and other ills may also attack us as we seem to become prey to every passing cold or other social ailment, and also see some deadlier or more debilitating conditions crop up in our age group, if not in ourselves.

Regular exercise comes to the rescue here as well. It can help with weight loss, or it can help with weight management once we get to our appropriate weight. Regular, moderate exercise can keep joints supple, in many cases even joints under attack by arthritis.
I know about this as I have been afflicted with fairly severe osteoarthritis for several years and manage to keep myself active and the condition somewhat under control by my own exercise activities. Exercise also strengthens the immune system, which helps us avoid or fight off the normal bacterial and viral infections which seem to come our way and which often seem to wreak havoc on the older population.

Even better; regular, moderate exercise seems to be somewhat effective in helping ward off such common companions of aging as high blood pressure, type II diabetes, and even some forms of cancer.

What exercise program is beneficial for fitness over 40?

In the first analysis, almost any physical activity which gets your heart rate up, makes you breathe more deeply than normal, and which challenges muscles beyond their normal range of activity is going to be on the list. There are people in their 80's hiking mountain trails, water skiing, playing softball, weightlifting (as pointed out earlier), or even cheerleading.
It is NOT necessary to take out a membership in a local gym, hire a personal trainer, or invest in a lot of exercise equipment and apparel...unless that helps get you motivated. Anything from walking, to swimming, to yoga, to weightlifting will generally fill the bill.

There are, however, some simple points to think about.

1. Get your doctor's approval first. "Nuff said?

2. Pick an activity, or even a group of activities, which you will enjoy doing. Don't be afraid to try something new...take some classes in yoga, tai chi, or even karate. Maybe you will feel better in a certain amount of solitude and just want to pick up a set of weights and exercise in the privacy of your home. Perhaps the idea of biking around the neighborhood or even around other parts of the country appeals to you. If this is a new set of decisions, realize that you may try a few things at first that just don't pan out for one reason or another. Keep experimenting until you find what is right for you. You are STILL exercising, right?

3. Put some variation into your exercise.

Any exercise cannot itself provide the three basic types of exercise needed. We need exercises which will stretch muscles and joints, exercises which strengthen muscle, and exercises which improve our cardiovascular fitness. This is not really hard to do, however, and should not take a lot of time out of your life, particularly when you consider how much it will put back into your life. As one example, you could do a simple weight or resistance training for strength two or three times a week, some sort of low-impact aerobics or walking for cardio on other days, and do some simple stretching exercises every day. None of these workout periods needs to be more than about 30 minutes, although a little more time and effort may produce better benefits, particularly once you have trained up to a level where your body is comfortable meeting the demands you place on it.

You are more likely to stay on a physical fitness regimen if you enjoy it. However, things do tend to get stale over time. It doesn't hurt to vary your approach from time to time in either the manner in which you do certain exercises, or by varying the exercises themselves. While not exact equals, for example, swimming, biking, and walking can be somewhat interchangeable as part of your fitness routine. In some cases, simply varying the environment, i.e. taking a walk in the park or botanical gardens as opposed your neighborhood may be all the variation you need to feel like you have put a little zing into your day-to-day workout existence.

4. Start off easy. At any age, a common reason for failure to stay on ANY exercise program is that people tend to try to do too much at first and try to progress too fast. Whatever you choose, your body needs time to adjust to the new demands being made on it, and results will never come overnight.

5. Don't stop. Probably the most important aspect of any exercise program, or any other self-improvement program, is the commitment to what you know you should be doing day after day. A haphazard approach to your exercise program is detrimental at any stage in your life. After 40, however, making sure you get your regular dose of anti-aging exercise is incredibly important.

6. Eat healthy. I try to avoid the use of the word "diet", and often substitute the term "healthy eating" instead. Diets don't work and can even work against you. They are difficult to stay on and take a major portion of fun out of life instead of making life better. Healthy eating choices will do the trick if you make them a regular part of your life.