I used to be very anti-gym for the longest. Once you get older, you really need to work at it unless you want to be like all your friends you see on facebook that have gotten fat as hell after high school.
I try to be active every day if possible. I walk to work and eat lunch at home so I walk 30 minutes a day even if I don't do anything else.
When I go to the gym, I usually do an hour on the elliptical with heavy resistance while watching skate videos on my EVO 4G, then I lift some weights for half an hour.
I have some weights, BOSU ball, pullup bar, and stationary bike at home. I work out while I hang out with my kids sometimes and I have some 3 lb and 5 lb dumbbells that my 3 year old son and 7 year old daughter use to mimic me (my daughter is notorious for overpowering bigger kids including boys in her karate class while sparring).
In my office at the hospital, I have a 25 lb. kettle bell (actually it's a kettle grip with weight from here:
http://www.ironwoodyfitness.com/equipment/kettle-grips/pair-of-super-kettle-grips.html, perfect pushup handles, and a exercise ball. I do a set every hour if I don't have too many assignments to complete (I set the timer on my phone to alert me).
One of my collateral duties in the navy (until my recent knee surgery) was to help lead the fitness enhancement program which means I worked out the overweight personnel in my command regularly to get them into shape. One of the workouts I lead them on was compared to the Bataan death march.
http://en.wikipedia.org/wiki/Bataan_Death_MarchIf you're going to run, be very wary of the toll that bad form will have on your legs. I didn't realize this until after I destroyed the meniscus on both knees due to bad form. This guy has probably some of the best advice for those of you who want to tackle running.
http://www.freedomsrun.org/Training/TrainingIntro.aspxI agree with the "getting out of your body what you put into it" logic with nutrition.
By the way, the human body is a total fucking asshole if you ever slack off and get fat.
http://www.npr.org/blogs/health/2011/10/31/141794801/losing-weight-a-battle-against-fat-and-biologyBest thing to do is never get fat. Good luck and goodnight.