Staying healthy according to the bible is staying away from sin because God made our body to be his temple. The Bible teaches that our bodies are like a temple where God’s Spirit lives. This means we should not treat our bodies badly. We should eat well, avoid harmful habits, and live in a way that honors God.
The bible also teaches us to discipline ourselves to have self control over some things and that's the way we can overcome sin. Instead, we should learn to control our desires and make good choices. When we practice discipline, it helps our body stay strong and our mind stay clear.
Rest is also very important in the Bible. God showed us the example of rest when He rested after creation. This teaches us that we should not overwork ourselves. Taking time to sleep and rest helps our bodies recover and stay healthy.