I turned 34 in February, once I hit 30 my right knee turned to shit, my sciatic nerve started to piss me off, oh and fucking hemorrhoids all of a sudden, plus so much more. I was always pretty active going to the gym only to do high weights, skating, basketball and then drinking a shit ton in my 20's...from the outside I looked pretty fit but it was all bullshit.
In the last few years I pretty much cut out the booze, I foam roll every morning, hit the gym 4 times a week and DO CARDIO, STRETCH, LIGHT WEIGHTS with HIGH REPS and CORE STRENGTHENING. Bed early and wake up early, drink a lot of water, Hemp seeds and Yogurt (probiotics), eat avocados, Bought a good bike and used it and just made sure to give myself a good warm up before anything excessive.
For food go to the health food area at the grocery store and get the bread that is in the freezer one slice of that with avocado and egg with turkey bacon on the side will keep you going all morning, for a between meal snack just have a protein shake and mix a banana, honey and anything you want really into it. Eating well is more important then cases of beer or pack of smokes.
In all honestly I know its fucking hard to stay motivated but getting older is happening no matter what, so you might as well make it as easy as possible on yourself. To start just buy a workout band and foam roller and youtube that shit...super easy to do at home. Oh, and make friends with a massage therapist who does deep tissue massages, fucking sucks but its great for you.
As a bonus your sex life will improve from all this....trust me.