Do as much math as you can. You can never know too much math or regret knowing more math than you use day to day. You can easily regret or become frustrated at not knowing enough math later in life.
The sciences, particularly those related to medical school admittance, are likewise difficult to go back and do. It is fairly easy to switch from the sciences into other fields like law, business, or the humanities. It’s much harder going the other way and attempting to transition from history into medicine or the physical sciences.
All learning is for a specific purpose. If you don’t know why you are learning something, stop learning it until you have a well understood and meaningful reason to continue or you’re just wasting time.
School is just a particular type of learning. If you’re in school only so you can go to more school later, see number 3 above and stop. Go to school to learn knowledge and skills that allow you greater opportunity to create the life and world you want.
You may not know what the life and world you want is yet. Focus on caring and helping others. Figure out what the biggest problems in the world are. Then figure out what the biggest problems in your nation are. Then in your city or town. Attack those problems you are most able to impact and see if you can help solve them. Start small if need be.
It is at number 5 immediately above that you will be happy you did marginally more math and science than you otherwise would have if you took number 1 and 2 on this list seriously. Many of the problems you will find in life require a lot of math and science.
If all else fails and you really don’t know what to do with your life, focus on making as much money as possible and try to give to people who are doing good work. The world could always be richer and it’s not a bad thing to get rich and use your money for good. Just as the world could always use more scientists, it could also always use more philanthropic entrepreneurs.