To be a fighter pilot get good grades, keep in shape, play sports, and take it one step at a time. Jr High, high school, College, Universal Pilot Training, more training, Pilot (in the long distance). Live day-by-day. Focus on your next test or your next game and keep flying in the back of your head.
If you want to be an AF pilot I'd recommend joining Civil Air Patrol (join a squadron that is on a military base, they're always more serious) and going to an encampment. You get to do fun things, like one-minute showers, 5 am PT, three-hour formations, and you get to hold your little blue book four inches from your face with your elbow parrallel to the ground for long spans of time, but it's probably a good indication whether or not you'll be able to put up with the basic military training (Academy, ROTC, OTS, etc). Personally, I left more fired up than ever.
However, one thing that amazed me about encampment was how many fat kids wanted to be pilots, so I must stress this; play team sports, the more competitive the better. They will teach you about leadership, teamwork, followership, aggressiveness and it keeps you in shape. You could tell instantly whether someone played sports because they were leaders, they worked in harmony with the rest of the team, they didn't make excuses, and they didn't huff and puff after running 100 yards.