>>1119757428 and people usually believe I'm younger (around 21-24). Same for my wife who is a Japanese immigrant. I'm also in my Senior year of undergrad so people don't expect undergrads to be that old. I was in the military for five years so that led to a late start in life.
I've never done recreational drugs, have no prescriptions, have never used tobacco, and do extremely light drinking. I'd guess maybe ~10-15 beers&shots for an entire year.
Unhealthy habits would be caffeine and salty foods.
I used to lift a lot until I got seriously injured last year, now I rock climb 3-4 days a week, and some cardio but not really. I can still easily jog 7 or so miles without being winded.
As for stress it happens (studying for grad entrance exams and applying in late round 3 or next year), but I'd say I very rarely get angry or dwell on the bad things, which I "feel" has the biggest impact on my age. I also was in a "numb state of mind" when I was in the Army waiting for time to pass as it's very robotic and almost no critical thinking.