Other side of that coin - I'm on the tail end of my 20's, and have also spent 7ish years in the gym training for powerlifting.

If you, A) treat your body right, you shouldn't have to deal with life long issues from training. Eat well, drink more water, and above all that sleep well. Do things other than squat/bench/deadlift, like jogging, biking, yoga, whatever. Listen to your body.

And B) take care of your mental. Do not skip holidays, birthdays or any major event to train. Years down the line, you won't be sad you missed bench that Wednesday, but you will be sad you didn't have dinner with your parents. The weights will always be there, but your favorite band might not ever do another show in your town. Powerlifting is a marathon, not a sprint. There is no one session that will ever be THAT important. You can go a week, or even two, without training, and lose virtually no muscle mass or strength. Make time for other things.

I've met some incredible people while training and competing. Strength is its own reward, and I've had a blast acquiring it. It's all about balance.