Sleep. Teenagers tend to stay up late often, if you sleep early and wake up early it should be able to strengthen the immune system and the mind. When your immune system is strong, sickness can be avoided, as well as zits and possible serious sleeping issues.
Water. People who drink enough water are able to keep their brains active and prevent themselves from being tired. Its good to drink plenty of water before exams, if you didn't know, the more our brains work the weaker our bodies get. We loose water and our food is burned up much quicker than when we are in our resting state.
