I have been a sick person since I was a child. When I was a child, my mother gave me more medical expenses than meals. Colds, pharyngolaryngitis and bronchitis are common all the year round, as well as rheumatoid arthritis, lumbar disc herniation and later hyperthyroidism.
Because my lumbar disc herniation has a great influence on my life and work, the doctor suggested that I swim to help me recover. I started swimming with a try. In recent years, I have been swimming (about 2-3 times a week) and benefited a lot. I am strong, I am not so afraid of cold in winter, my face is rosy, and I seldom catch a cold. Many colleagues and classmates around me have caught a cold several times, and I am fine (arthritis has not worsened). My relatives and friends say that I have changed a lot.
But people who are weak must pay attention to "step by step" in swimming and fitness. Before entering the water, they should do enough preparatory exercise, insist on exercising in the water, don't stay still in the water, and take a shower and change clothes as soon as possible to keep warm after entering the water. At first, each tour should not be too long, about half an hour is enough.
Don't swim when you are hungry, full or tired.
There is also the need to persist in order to be effective. Otherwise, if you swim once or twice occasionally, you will only feel backache and bone pain, which will not have much impact on fitness.
The above suggestions are for reference only and I hope they will help you.