Only have 30 minutes for a workout today. Walk/Jog combo or body weight exercises?

Look up some HIIT workouts on youtube. They give you the most bang for your buck when you are short on time. A good 15 min HIIT workout can be as effective as a steady state cardio workout twice (or more) the amount of time.

30 minutes isn't long enough for an effective walk.. So, if you'd like to do cardio I suggest doing a moderate jog for 25 minutes then try to sprint for the last 5. Body weight exercises are great and plenty can get done in 30 minutes but of course while you'd be building muscle, it would take longer to burn fat by just doing weight exercises. You could also do a fast jog for 15 minutes, then do the other 15 minutes of body exercises.