Had 690/690 SAT, 29 Math 30 English ACT, 19/97/17:52 (292) PFT, three leadership positions in Scouts and Sports, 4.0 weighted at competitive Catholic HS (no ranking) with a boatload of APs and Honors, additional letters of recommendation in addition to those required. Yeah, I'm one of those kids who over-prepared, but since this was something I wanted, I wasn't going to ease up.
One thing I would recommend to all those on here is to run. I ran cross country throughout high school, so it comes easily to me, but running a 6:00 mile three times is not something easily attainable. There were so many kids who got 15-20 pullups, did 80-95 crunches, and then dropped a 20:30 or 21:00. I know some people are built different than others (I'm tall and thin), but running proved to be the insurmountable wall for most people.
Last but not least, be confident in yourself and your abilities. You've made it to your senior year; the only person who can hold you back is you.