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Your body is almost two-thirds water, so staying hydrated is important. Teenagers should aim to drink six to eight glasses of water per day, according to the British Nutrition Foundation. That number increases for teens who engage in sports or are especially active. Other good sources of fluid include 100 percent fruit juice and low-fat milk. Sugary and caffeinated drinks should be limited or eliminated from the diet completely as they provide excess sugar and empty calories.

According to the Cleveland Clinic, teenagers need at least nine hours of sleep each night to function at their best during the day. It sounds easy enough, but with early school start times, late afternoon practices and hours of homework, getting enough sleep can be a challenge. Set a regular bedtime that allows for nine hours of sleep before you have to get up for school. You should also plan for at least an hour of "quiet time" prior to bedtime. The goal is for all electronics to be turned off for the night so that the brain and body relax. Quiet time may involve listening to soothing music or reading a book.