Assalamu Alaikum, after reading your post, many questions arise, but the answers to some of them are that the life of a human being includes the fact that if Allah created him, he has to go through every stage of life. Of course, whether he is young or old, surely a person stays healthy by exercising, but along with this, good food is also necessary for a person. He is saved from pain and many other diseases, but life and death are in the hands of Allah. If you suffer from tension or depression, it also has a very bad effect on human health, so try to avoid simple food and wasteful activities. Thank you.