Second, it's ok to let things slide for a while, but the longer you let them slide, the tougher they are to fix (and if you wait too long, some things can't be fixed). See plenty of other comments about teeth, back, RSI, diet. If you decide to let something go for a while, pick a time to follow up on it, and reevaluate.
Third, problems get bigger, stakes get higher. But you'll learn more tricks for coping with those problems. Sorta grim, but suicide rates by age climb till 50ish. around then you'll have (sorta) seen it all, there's not much that the world can throw at you that'll put you in a complete tailspin.
I can't tell you how to live your life. I'd suggest, be true to yourself, be true to your ethics. If you don't know what those are yet, try to figure out who you are. When you're stuck in a stressful situation, at the end do you want to feel vindicated? do you want to have a great outcome for everyone? do you want to just leave it all behind? Do you want to just grit your teeth and get through it? Those all point to different values, and can help you figure out who you are.
Some people age gracefully and some don't. some people get to make choices about that, and some don't. It's going to be ok. Everybody gets through their life one way or another.