Long Post so feel free to ignore.
As I get older I don't need rippling chest muscles or shoulder muscles but I do need rippling back, wrist and calf muscles.
So in port I go to the gym 3 or 4 times per week to do 3 types of training: Weights, HIIT Cardio, and, Old Mans Exercises.
My diet: Low Carb, no processed food, no or little sugar (except beer sugar

).
Vitamin supplements: D3, K2, (taken at the same time); Zinc and Selenium (taken at the same time); Magnesium, Potassium, CoQ10
Most of my stuff is backed up by research but the Old Man Exercises have been devised by myself and freak out the Gym staff.
As I get older I am concerned with:
Heart: CAC Score - coronary artery calcium - which shows how much actual calcium has built up in my arteries (Very, very little).
Cancer: Cancer cells eat sugar to grow so I keep the sugar down.
Back pain: So I have exercises just for that.
Walking so slowly the Grim Reaper can catch me.
Falls: One bad fall can be catastrophic.
Problems: Back muscles dont actually exist where I need them! Theres no muscle that covers the lower back, the Lumbar Spine area. You don't believe me? Even Arnold Schwarzenegger NEVER had muscles over his lumbar spine!
Google "Bodybuilders Christmas Tree" and look at the images.
You can see their spines...!

All of the muscles are either side, above and below, but not on or around. Weird, huh?
The gap is called the christmas tree because thats what it looks like.
Philosophy: To use science to get the best benefit from the least effort and least time exercising.
Weights: The normal stuff that the gym junkies do but I try to do heavy weights to failure in 4 to 7 repetitions. Then some days light weights to 30 repetitions till failure then drop the weight and keep going till total failure.
HIIT Cardio: We are told to do a few hours of 'brisk walking' every week. But whats Brisk Walking? From the NSW Institute of Sport the idea is we need only have 15 minutes 3 times per week with the heart rate above 150 beats per minute. The difficulty is its desperatly difficult to get it up that high for that long... so they devised a method to trick the heart so it goes up and stays up with the least effort.
On a cardio bike set quite easy (about 5 or 6) I do a 7 second HARD as I can and then 13 seconds very soft, just my legs going around. Watching the cycles clock I do my hard bit at 20; 40 and; 00. Within about 2 minutes the heart rate is up. If it gets too high I cut from 7 seconds to 5 or 4 or even 3 seconds and increase, correspondingly the relax time. 15 minutes is not too difficult.
On the Treadmill walking I set the Incline to the maximum of 15% and the walking speed very low, 4.5kmph. As the heart rate comes up I keep dropping back the speed, not the incline. After 15 minutes Im down to 3.5 kmph - quite easy. 15 minutes no trouble.
Old Mans Exercises: These I have developed myself and get ridiculed by the 20 year old gym instructors.
Picking up dropped keys is done (until were being watched by a fitness guru) by bending down and picking the damn things up. NO! says the guru, I must squat down, back straight to pick up keys, or lift a small weight! But squatting down back straight I cant see the keys, all I can do is feel between my legs for them.
Tying my shoes is done with a bent back. Try tying your shoes with a straight back. impossible.
On a boat twisting whilst pulling is derigour. We all know its "bad" for us but what else can we do?
Instead of saying I can't do this, I have devised Old Mans Exercises so I get muscles to pick up keys, tie my laces and twist while I winch or haul up the halyard or get a bucket full of seawater up the side of the boat and down the companionway.
Bent Back Lifting.
Using the Back Extension equipment at the gym I'm told to keep my back straight... ok I do a few reps like that. But then I drop down chin on chest and back bent and slowly uncurl to horizontal.
Key Drop: I put a light weight on the floor and bend over with bent back and pick it up. Careful to use light weights!
Shoe tying: Situps with bent back.
Barbell behind the back: A light barbell behind my back and lifting it from butt to as high as I can go.
Wrist strengthen: Barbell to do a bicep curl but a bit lighter, after the first curl I open my hands and let the bar roll to my finger-tips then roll them back up into the next curl. Great for forearms and wrists.
Twisting Theres a new machine there i sit in it and twist my upper body. start with a small wieght and note I cant twist far... but now its getting better.
Old Man Jogging: on the street I do about 3kms in 15 minutes. Lil Old Man steps, Ive only just started and its not going too bad at all. Just short and slow.
Walking faster than the Grim Reaper:
We know from Hollywood that the Grim Reaper walks slowly with his scythe mowing down anyone he can catch. But in real life could this be true?
Yes!
And a few scientists tested men to find out that you must walk above 2 miles per hour/ 3kmph or the Grim Reapers gunna get you
https://www.bmj.com/content/343/bmj.d7679
So if Im going for a walk of any type I make sure im doing more than 3kmph! simple.
Falls: With gym, walking faster, a few jogs and old mans exercises I am less likely to fall... and if I do my wrists are stronger to allow me to hit the deck without broken bones or ripping tendons.
Conclusion: I see lots of older folks who are unfit... but very very few 75 year olds who look like they work out. Ive started now with the long term view, investing in my health so I can enjoy my other investments.
Mark