Realistically, you should be able to do maybe 15 pull-ups, and fifty sit-ups and push-ups. It doesn’t take long to work up to that. just add two or three every day. Also, build your run up to 4 – 6 miles if thats possible. Run at least 5 days a week and do the upper body workouts at least 4 days a week.
You need to be in good enough physical conditioning so that your muscles don’t become painfully sore and you become discouraged and drop out after a few days. 😳
Also, if possible, swim and do other aerobic sports. It all counts towards conditioning, which is what you’re after. 😳