I'm 71, 5'10'' and 155 lbs.
After reading this I was curious to see what I could do. I did 18 slow, perfect, push ups. Real ones.
I was surprised that I couldn't do more. 50 years ago I could have easily knocked out 30-40 and I was probably the weakest guy in the crowd I was hanging out with. And that was during the time I was smoking (2 packs a day), doing drugs (just pot) and not yet running.
Some one else remarked that back when he was a kid there may have been one fat kid in the class. I remember those days. I remember thinking that Jackie Gleason was obese...OBESE! By today's standards he would just be overweight.