I'm taking my health for granted!

You guys, I turn 21 Friday & I just realized that I'm totally taking my health for granted. I only weigh about 125 and my body looks good minus the little pudge that I have but when I'm around plus size women, I feel happy that I'm slim rather than feeling humble because I just realized that that could very well be me if I don't change my life around. I'm so disgusted with myself for even acting arrogant like that. Just because I look small & healthy, I'm really not. I need to realize that my health could be taken from me in a blink of an eye! I treat my body like straight sh*t just because I know that I won't gain much weight. And for this reason, I need to create a healthy lifestyle for myself but I can't do it without help. I've tried and have committed to healthy lifestyles time & time again and I realized that I can't do it by myself anymore. I need help! But I'm in college, I don't have $ for a trainer or anything. & I tried to get my boyfriend to workout with me but he always cheats (on diets) lol & my close friends don't care to get healthy. And I always try to find workout partners here on campus but it just never goes well so what should I do?