I hate running too which is why I so hot yoga haha
have you consulted a doctor to see how much weight you should lose?
transitioning into highschool can be hard, especially because your body is going through major changes. (puberty) for girls, we fill out and gain weight faster than boys,so while were like full grown ladies, guys are still like 4 foot lol
anyways, please make sure that 100 lbs for you is a realistic goal...