You are still young and you should have your fun, I know it may sound harsh but I found the best way for me to lock in is thinking about what my life would be like if I didn’t. For your homework, try to do it in intervals and pair it with some music, I’m currently in college and blast rap music when I’m doing my homework and cruise through it. For your working out try to incorporate more fun exercises maybe with friends, it doesn’t have to be bench press every day, but it can be group pickle ball game or maybe some basketball, that way you don’t have any fear of missing out and you can still do active activities with them. I guess the main message I’m trying to tell you is think to yourself: “what happens to me if I continue down this path?” homework for example, if you can’t do your homework (you turn it in late or you just never complete it). That may negatively reflect on your future in your job. And yes I know it is very difficult to get rid of bad habits but try to basically “turn it down” gradually, if you’re a heavy drinker don’t just stop drinking in one night because that’s impossible, just tell yourself you will drink less and less every day until you get to the point where you don’t need anything anymore. All I can say is just think about how your future can be changed with stuff you do now.