I have been keeping fish now for 24 years. When I started at age 51 despite being 140 lbs and 5'5" tall I could fill a pair of 5 gal. buckets with water and carry one in each hand the length of the house from a bathroom out to the screen terrace. I also used my bathroom as fish central for doing water changes. This involved 32 and 20 gal Rubbermaid garbage cans and a few 5 gal. buckets. The 5s were normally ppicked up and dumped into the buggers cans being empied with a pump.
Today I do not carry filled 5 gal buckets anythwere. When I am ready to dump the water from one into the bigger can I actually use a specimen box to scoop out about half before I life the rest and dump it in.
Over the years I ramped up tank numbers. So I was getting plenty of exercise. I can tell you one cannot stave off old age in terms of strength. Of course there are some exceptions on both sides of this.
Today I am a couple of inches shorter and pounds lighter. Gravity is not your friend. I am backing out of the hobby because I cannot keep up either strength or stamina-wise.
A number of my tanks have required I use a small folding ladder to be able to do weekly maint. I have escorted both of my parents through old age and death and watched how falling became a problem. Bones get broken. I am doing away with my bigger tanks because I know sooner or later I will wind up falling off of the ladder.
I also no longer work in the woods with my chain saws. I drive my car closer to the speed limit because mu reactions times are not what they used to be. Etc. Etc. No amount of will nor dedication will keep us from physically declining as we go deeper into the "golden years."
Three things I have gleaned from it all about old age and it can be explained by three sentences.
1. And you know that you're over the hill when your mind makes a promise that your body can't fill. . Little Feat - Old folk's Boogie
2. Paraphrasing: Death is nature's way of telling us to slow down.
3. If you wake up in the morning and nothing hurts, you are probably dead.