When I joined the Army in April 1969, I was about 260 pounds and not in great shape.
When I jumped off the deuce-and-a-half in the company area, all the drill sergeants gathered around me, saying, "Oooh, looky here. We got us a fat one." They then proceeded to work me over mercilessly with push-ups, sit-ups, low crawl and run, run, run until I was ready to drop (and did quite a few times). Because I got up every time, they eventually treated me more and more just like everyone else (as Vince Lombardi was accused of, "like dogs").
I went into basic combat training a scared fat kid but came out as a confident young man in the best shape of my life, before or since. I never did thank all those tough old drill sergeants, but I want them all to know now that their work and inspiration to me put me on a great pathway for a full and productive life. I still think of them often and wonder what happened to them.