Swimming workouts (doing laps) are primarily aerobic exercise, but at the same time a form of resistance training, the water being the resistance. Sprint laps, on the other hand, can be highly anaerobic.
The density of the human body is very similar to that of water. So your body, to some degree, is supported by the water, therefore placing less stress on your joints and bones. For that reason, it is often used in rehabilitation after injuries or for those with disabilities.
I learned to swim as a kid, and I was surprised recently when I read that a fairly high percentage of youngsters never learn at all. As I understand it, Olympic and world champion Michael Phelps plans to dedicate much of his time to improving on those percentages.
A martial arts back injury as an adult got me back into the pool again. I was at a point where weight training or running irritated the injury, and I was really out of shape. So I decided to try swimming. I lived then in San Francisco and I went to the famous Fleishhacker outdoor pool, which in those days was one of the largest, if not the largest in the world, at 1000 ft. in length.
Fleishhacker was near the ocean beach and was filled with cold salt water piped in from the Pacific. My first time there, I got in, shivered, and managed one lap across the width — not the 1000 ft. length. Next visit, two days later, I went across the width twice. And therein is the simple secret to an exercise program. Get so you can do one lap, and progressively keep adding to it.
Slowly, I worked my way up to going a mile. Then I joined an informal group that would do a mile a day. We swam rain or shine. Sometimes during heavy storms the lifeguards would watch us from inside the adjacent building. It was fun and the people were good to be around. The facility closed in 1971, and the San Francisco Zoo, which was next door, got the property and covered over the pool. Some of the mile-a-day folks joined the Dolphin Club or South End Rowing Club and continued getting in their miles in S.F. Bay. I entered a few of their organized events and races and decided the water was too cold for me to make it fun.
What I can tell you about doing laps is this: As repetitive as it is, I did not find it boring. It was instead a kind of meditation. Once you get to where you are comfortable in the water, you go into an “automatic pilot” state of mind. It's good and it's healthful. It's stress release of the first order.
Don't resist trying because you cannot swim now or you can but are not very good at it. If you can manage only a single lap, you can get better by doing it the same way I did, by adding another lap as you are able to. Or, better yet, get some coaching and learn to improve your form and stroke at the same time you improve your endurance.
Even if you can’t swim a stroke, it’s fairly easy to find a teacher. A good place to start is at the web site below: