To be with a good athletic training, strong and health you can start to train at the gym.
You can become a famous sportsman just like Michael Jordan or Pele.
It will assure you slim and health body for rest of your life.
Off course some sports are very dangerous and unhealthy and you should know about it. For e.g. box won't guarantee you long life and strong body. This sport can damaged even your brain.
I suppose that everybody knows Muhammad Ali, the most popular boxer in the world. Unfortunately, this powerful sportsman is very sick. Doctor's diagnosis was Parkinson disease. Now, his life is in dangerous, he is nearly to death. The doctors said that the fights damaged his kidney. Now, when you are looking at him, you can't believe that this poor, sickly, middle-aged man was the most famous boxer. You see that you have to be careful when you choose the sport, box won't guarantee you health.
REMEMRER THIS!! IT IS NOT THE WAY!
You can't overwork. That's why very dangerous is running on long distances. Athletics have got very special lung capacity. This capacity is intensive training's result. Unfortunately it can lead to heart attack.
Nowadays people don't have to use their muscles to get food, they don't have to run from dangerous animals. We don't have to be proficient to survive, because even when we fall ill we can call a doctor. Maybe we are living longer than people used to live in antique, but there is many proofs we don't live RIGHT.