Law school will teach you how to think about things in a lawyerly way, you will learn a new language - legal jargon or legalese, you will find that your tolerance levels will increase higher than you ever imagined, you will find that you are able to do things you did not realize you could do. Many people describe law school as a mental boot camp or liken it to pledging a fraternity or sorority. These are good analogies - law school is difficult and the only way you can get through it is if it is something you really want. You need to talk to as many law students, law graduates and lawyers as you possibly can. Read as many books as you can, talk to your pre-law advisor and professors at your undergraduate university who hold law degrees, visit law schools, talk to everyone who will take the time to chat with you, sit in on classes, make appointments to speak with administrators and professors.
Law school is a major step, a huge investment - timewise, financially, intellectually, emotionally.
For many people, it is the three or four most rigorous and challenging years of their lives. Just be absolutely sure that it is something that you really want to do. Enduring these things will undoubtedly help to prepare you for law practice or for whatever other route you decide to pursue. You will definitely leave law school a much stronger person and thinker than you were before you walked through those doors. It is not something that a person can get through or even pretend to enjoy if it is not in his or her heart, or if he or she is not sure of how the training will connect to future ambitions and goals.