You are exposed to more risk (I'm recovering from a minor strain in my lower back from deadlifts - I'll be more conservative next time), but I think in the long run, the rewards outweigh the risks.
Bodyweight squats are good. So are chin-ups, pull-ups, dips, push-ups, burpees and planks. I'd avoid sit-ups, especially if you hunched over your desk all day. A fun way to spice up the workout is "Parkour".
My workout is running a few kilometers to a selected tree, doing some of the exercises above and running home. Takes about an hour each. Three times a week.
It's been good - it's a program of pull-ups, push-ups and squats with 3 sessions a week and a series of levels to work through. Pretty nice if you're busy, none of the workouts go past 30 minutes because there's a focus on high intensity in the workout.
Probably wise to take the guys nutrition advice with a grain of salt, since it doesn't see to be his main area of knowledge.
Other than that I run about 5km 3 times a week.