In Thai high school don't different middle school, but in high school will study harder. High school life have a fun, tired ( it's normal ). When go to high school, the first important is your friends( if you have good friends, you will pass the high school life. About learning in high school you much intend to study very much( if you want a good life in future ), but don't serious about learning more ( it's really a important but if you serious more, you will be nervous ). There is so much diverse, but every thing depends on you ( you can select your life ). I hope every thing goes well. Good luck my best friend.
Ps. Don't serious every thing that have not happened, because it has not occurred.