Disagree with bomerr. The most selective schools are full of students who prove deepseafishes point. And they aren’t just recruited athletes or award winning concert musician. Most have just one or two sincere interests in which they have invested themselves in unique ways. Meanwhile, pity the poor admission officers who read application after application with the same mix of school clubs w leadership position, school sport, obligatory volunteer experiences…these well-rounded types are a dime a dozen. They will get in somewhere (the same place they would have gotten into by being less well-rounded) but have burned themselves out in the process checking off meaningless boxes and padding their resumes.
Your goal is to be you as hard as you can which means putting your energies into what you care deeply about. It makes for a much more interesting application, interview and person - and more importantly, a rewarding life.