Staying Healthy is God's will for us. He wants us to be healthy. He says in His Word that He wishes above all things that we should be healthy. Good health is what we were created to enjoy. God created us to enjoy a good life.
There are things which we have to do in order to enjoy the good life. The Bible is not only a book of doctrines. Yes, the Bible teaches us to do good works and to obey the commandments of God. But it is not only the doctrines which we are learning in the Bible.
The Bible teaches us that exercise is good. It tells us that we should engage in exercise. Whatever that the Bible is good, we ought to do that because it will truly profit us. The are many things which the Bible says that we should we should do because they will favour us.
The Bible says that bodily exercise profits little. That little means a lot to our body. That little is enough to keep one health all of his life time.