I know it's hard to see from your viewpoint (because you're experiencing it in real time), but you will only get one chance to be a teenager; go with the activities that you like the most, the ones you get the most enjoyment from. You'll have the rest of your life to work on your resume. Good luck!
Wishful gave the BEST advice. PLENTY of people receive appointments to the academy without ever being in JrROTC, Scouts, Civil Air Patrol, etc. MANY are involved in band, clubs, and other activities. I only bring this up, because I don't want to see a bunch of 9th and 10th graders (Or their parents) reading this or similar threads, and believe that they NEED to get involved with scouts, CAP, or JrROTC. You DON'T HAVE TO!!!!
Get involved in the activities that you enjoy and are passionate about.
Take on leadership position in those activities.
Excel in those activities and show growth, leadership, and TEAM involvement.
The only activities I would stress that is pretty much universal for all applicants, is organized sports. And NO, it's not for physical fitness purposes. That's not why the academy puts so much emphasis on organized sports. If you don't know WHY sports is so important, there is a sticky at the beginning of this forum on why athletics/sports is so important. READ IT!
But as far as scouting, cap, and JrROTC go. IF you're into that..... than do it. And do your BEST at it. Rise in the ranks of leadership and improve your team building skills. If you aren't into scout, CAP, or JrROTC. DON'T sign up for those just because you think that you're "Filling in some square". You will simply be WASTING your time. You CAN'T excel in an activity if you aren't into it. If you're not passionate about it. Find the clubs, band, theater, class officer, 4H, or WHATEVER extra curricular activities that you are IN TO, and excel at those. Develop your leadership and team building skills. Be involved in things that are BIGGER THAN YOU. Volunteer your time and skills in helping others, your community, your church, etc. Be involved in TEAM activities (especially organized sports). Show that you KNOW what it's like to be part of a TEAM. That is what the academy and the military is all about. It is the ultimate TEAM. NO ONE can succeed in the military as an INDIVIDUAL. Academy basic training and the academy itself is purposely set up so you CAN'T SUCCEED as an individual. The academy's goal is to make you a "Military Leader". And even as a LEADER, you have to be part of the TEAM. And you can't learn how to LEAD, until you know how to FOLLOW.
Best of luck.