Like the previous posters mentioned, it all depends on your definition of success. If you want straight As - plan to study all of the time. Being in a small class with the same people day in and day out and seeing who got on the President's List (4.0) last semester, it's pretty safe to say that those people study constantly except for the few lucky bastards who are just that smart.
I used to be an A-grubber, but since pharmacy school I've mellowed out a bit. I still maintain the best GPA I can without going overboard (my goal is to stay on the Dean's List every semester) I mean, these are some great years in my life and I want to enjoy them, I don't want to graduate close to 30 years old and go - what in the heck happened to my 20s? I have a husband, and house, volunteer work and hobbies, not to mention a job. But that's just me and I digress 😳
If there is ONE thing, ONE piece of advice I can give people, regardless of their educational or GPA goals it is this: do not procrastinate. Let me say it again for emphasis: DO NOT PROCRASTINATE. If you are by nature (and I am) a procrastinator, it's time for a study-habit overhaul or you're going to find yourself in big trouble in no time flat. I don't have nearly the social life I had when I was 21 and single (for obvious reasons) but it is possible to have fun and go to school - in fact you should!