Paul,
It is strange what we do to our bodies... I worked my entire working career as a desk jockey, so I got excerise when I had to go to the file cabinet or to get another cup of coffee, then to the head to get rid of the coffee....
I never was one to exercise much though. I did yard work and such and anything I thought I could tackle, but nothing really physical for any extended period of time. I'm fortunate that I have a relatively high metabolism and most of my life didn't eat a lot. I'm about 6'1" and weighed about 150-155 lbs from when I got out of the navy until I married again 18 years ago. Since then I've gained about 40 pounds and can't seem to get it off. I was single most of my life, except for a short marriage in the early '70's, so I probably ate only when I thought about it. My wife is quite a good cook and serves meals on a schedule... now that I've reached the top end of the 60's age bracket, I find I'm not so active as when I was 30 or 40 and probably not near in the condition I was then either. My muscles get sore much easier than they did then.
A few years ago, I was trimming some trees in the back yard and used my belly as a brace for the trimming pole. I would set the pole against the belly and then pull down on the rope with both hands... in doing so I opened a hernia in my belly just above the navel. Doctors said it wasn't serious and as long as it didn't bother me not to worry about it.... in September, it became strangulated and required emergency surgery. I wound up with an 8 in scar down my belly and about 5 or 6 inches of small bowells removed where it had become strangulated. I'm over all that, ever so often I'll feel a pull on the scar tissue in my stomache, but I now know to watch when I do things and pay attention to the body. I'm sure my stance is all wrong for what I do with a chain saw... I only use one to cut up the logs I've collected for bowl blanks and such. After a couple of hours, I really feel the muscles in my lower back straining and pulling.
It's hell getting old.