I've talked about this before, but getting older doesn't mean that you have to fall into the same pitfalls that your parents did simply because you're the same age. If treated properly your body should feel pretty dang good at 30, 35 and on up (I'm not yet qualified to say how good 'on up' should feel, stay tuned to this blog for updates).
Conversely this is not permission to shirk responsibilities. Shirking responsibilities has consequences. Please do not complain to me how 'unfair' it is when those consequences come to call.
Exercising into adulthood is about the 5 P's:
Planning: When you were 19 you could just go in and hammer out set after set, you didn't need to manage your time. Now time is limited, as is your recovery. Get in execute the plan, and get out. If what you're doing isn't working, change the plan.
Preparation: warm the hell up. Foam roll, get some mobility work, and get a little sweat before you get under heavy iron. Old age is the accumulation of injuries. Prevent aging by: not getting injured and treating the injuries you have.
Parlay: Negotiate. Make sure that those to whom you are responsible (boss, wife, husband, kids.. whomever) share your vision on the importance of exercise, and talk to them. Negotiate times that are for you to go play/exercise.
Priorities: I would love to train with a local wrestling club, I would love to go to a judo school and work on my gi throws, these are not a priority right now. So they get back-burnered for lifting and BJJ. When I lift I generally do 3-4 movements, I would love to do 5-6, but I have time for 3 so I prioritize the best most important movements for me.
Play: it's gotta be fun. Exercise should not be a grind unless it is a short term preparation for some sort of competition. Once it gets to be not fun, change it. Do something different. Nothing will make you seem younger than throwing yourself into an activity with an utter disregard for yourself.