Beyond taking STEM classes, to achieve your goals it's important to avoid doing things that will begin to make you drift away from your dream. Don't get caught up in drugs or alcohol, stay physically fit, develop a routine and think about routine as your training partner. When you're young, your behavior is malleable and easily shaped, as you get older it can become harder to change your ways. It is easier to stay right-minded than it is to get right-minded.