Stock the house with healthy snacks and serve nutritious meals. They are likely to enjoy making plans with their friends and they may spend time together working on goal-oriented projects with their friends. Most teens experience great fluctuations in their self-esteem. Most females have started their menstrual periods and have experienced breast development. How to Raise a Happy, Healthy Teenager. Common Milestones Seen in 2-Year-Olds. Get purposeful about teaching them life skills and give them opportunities to practice those skills on their own.