Do not compare yourself to others. Life is not a race. Read as much as you can. Learn about finances. Find a mentor. Pick one or two hobbies and seriously pursue them. Your smarts will take you nowhere. Become disciplined. Stop drinking sugary sodas. Steal money from dad and invest in Apple.
Ignore everyone, their standards, and set/pursue your own standards and curiosities.
You will meet many people older than you that are full of their own doubts, and think they can't beat their own doubts so they might get you doubting yourself. Run like hell whenever someone shows this.
Read PG's essay geared to students, it sums up a lot of the great mentoring advice I got when I was 16 and doing things I had no business doing at that age:
http://paulgraham.com/startupideas.html
Ps., the above essay isn't just for any startup ideas, but anything you tinker around with and pursue.