Whats a good stress reliever?

I'm in the IB program at my school and it gets very stressful. I'm contemplating dropping out of the program but I know my parents will not approve because I've made straight A's all year. However the course load is so heavy that during the year Ive forgotten to eat. I dropped 15 lbs this past yr and next year i will be a Jr.( the most stressful year). How can I chill out and relax? I never have time for breaks