How to Get into Harvard and the Ivy League, by a Harvard Alum: https://blog.prepscholar.com/how-to-get-into-harvard-and-the-ivy-league-by-a-harvard-alum
There are some things I want to point out before the article begins. First, this article is -mainly- for students who are spending hours on AP classes, extracurriculars, and/or volunteering work they are not passionate about, probably being unhappy and stressed as a result. Not only this an undesirable state to be in, but also fulfilling all these demands is not even the right path to be accepted by highly selective college!
Second, record this into your head: joining an Ivy League college doesn't determine your success in life. It can certainly be beneficial and give you -maybe (?)- an advantage in the work market, but the name of the college you attended is not going to make your future. Some people in the Ivy League wind up doing nothing with their lives; on the other hand, some people who attend mediocre colleges end up accomplishing a lot. It’s your ambition, passion, and discipline -and a bit of luck- that can guide you to your dreams, whichever they are.
Also, if instead of miserable you are happy joining a bunch of extracurricular activities, doing volunteer hours, being part of a team... keep on doing it. You learn how to interact with different people in different circumstances, pick up different skills, and can be part of something really big and amazing. As long as you’re growing and learning, every second of whatever you’re doing is definitely not a waste of time.
This final point doesn’t have much to do with the article’s content but is still worth mentioning. There’s so much more to life than attending a highly selective college; do not neglect other areas of your life -particularly those that make you happy- by obsessing with your college application.
Now, on to the advice. This is based on writings by Allen Chang, co-founder of PrepScholar. He has guided thousands of students to success in college admissions and in SAT/ACT prep. Allen himself is a graduate of Harvard university.
There is a critical flaw to being "well rounded". A typical student that is trying to be well rounded is one that joins a bunch of extracurriculars, plays a JV sport, gets straight A's in all classes… The problem is that being well rounded means being mediocre -or okay- at everything. Mediocre blends with the crowd, and what you want is to stand out from the thousands of applicants these colleges receive every year.
Highly selective colleges would rather have students that do really well in one specific set of skills. Your passion is key here, but also is developing your strengths: to become really good at something, it takes relentless focus and putting in all your effort (100% or even more!). This spike in your skillset can be achieved in many ways: If you’re passionate about a unique cause, try to start a club or a non-profit group. If you are interested in a particular subject, try to find a nationally ranked competition that you can rank well in. Or even if you have a simple hobby that you enjoy, like doing makeup, think about how you can showcase your talent, and receive national recognition for it. For example, starting a Youtube channel for makeup.
Nevertheless, you don’t have to demonstrate to colleges success in whatever field you aspire to be in the future or to be a master-genius in said field. It is more important to demonstrate your potential; colleges want students that are going to accomplish world changing things.
Even though you’ll put most of the work in a particular set of skills, do not forget other aspects in the application are important too. Generally, you need strong academics. You need good GPA/test scores, and you should have excellent grades in whatever field you are passionate about. For example, if you are a science geek, it's okay if you score B's in social studies and writing, but you should receive excellent recommendations and grades in science. You should also be successful in science extracurriculars.
Extracurriculars that you would think schools would fix on, such as athletics or musicianship (playing an instrument), are not really sought for by highly selective colleges, unless you’re a team captain, a stand out player, a (music) section leader, or captain master. Volunteering as an extracurricular doesn’t get a lot of attention, either.
However, if you truly enjoy your extracurricular activities, keep doing them, even if they don't strengthen your applications. If you feel like you have a true obligation to the group, and it's painful to think about leaving them, then continue to do it. Remember that it's important to do what makes you happy and things that are meaningful to you, regardless of their “usefulness”.
The best predictor of future achievement is past achievement. The point is to convince schools that you are going to continue achieving and succeeding in great things, college and beyond.