I was not in the military. But I graduated from NMMI. PT was at 0600
We ran 2 to 4 miles three times a week. Push ups, sit ups, pull ups, flutter kicks etc.
I am still the same size and weight as in high school. Diet is 90% of what you look like. Working out makes you stronger.
I'm turning 40 in a few months.
Minimum: 10,000 steps a day. It is harder in the winter time.
To avoid injury: Warm-up and stretching are more important now for me than in the past.
I am about to start my "get ready for summer" workout.
5lbs dumbells. All arm excercises, except bicep curls. Pull ups work the bicep in conjunction with the other arm muscles. I do squats and lunge squats with dumbels.
I have lifted weights seriously. I didn't stretch enough and ended up getting tennis elbow in both elbows. VERY PAINFUL. I did gain 12lbs of muscle in a couple years though and was able to maintain less then 10% BF. For my body type, my vegetarian diet, and my T level: this was pretty decent.
If this looks familiar: This is the barracks in "men who stare at goats"