Sleep.
To function properly, your body and mind need from eight to ten hours of sleep each night: have a routine for going to bed and close the blinds or curtains before you go to bed and minimize any light sources in the bedroom.
Diet.
Eat a well balanced diet: drink plenty of water, eat a balance of meat/protein, whole grains, fruit and vegetables daily, don't skip breakfast (Eat something for breakfast everyday), eat regular meals.
Physical Activity.
Exercising regularly is part of having a healthy lifestyle. Physical activity helps build a strong body and mind.
Play.
Another important part of having a healthy lifestyle is remembering to "play". Just taking time to laugh, have fun and being around people who make you feel good is part of having balance in your life.