How to survive high school is a mystery, its very strange and awkward years of your life, and i guess in order to survive is to learn everything they teach you and probably not use this site because of it giving you the answers and you wont learn it unless you get someone really awesome to explain how they got the anwser. so i guess you need to have skills in reading, math, scocial studies, and science, and what ever other classes you have. thats the best i can answer such a weird question.
Habits can be difficult to develop, but not if you use the correct strategies. Establishing a daily gym routine will be easier if you already have a once-weekly gym routine. Being held accountable to another person increases motivation. If you slip up one day, don't stress. One small mistake will not erase the work you've already done.
hope this helped, have a great day :)