As we're talking about getting old and retiring. Quite a few of us aren't in our youth any more. I turned 54 a few weeks back, so don't consider myself old. I can't remember the last time I was sick, I'm super-fit and healthy, never felt better.
One of the most important things as you age is to retain muscle-mass and not succumb to sarcopenia - muscle wasting. As soon as you lose it, you go downhill very quickly.
So resistance training is a must - lift heavy things, regularly! Move a lot too, not necessarily vigorously, but just plenty of it. I have my Apple Watch movement ring set to 1000 active calories and I close all three rings daily. Keep active. Lift. Have a circle of friends. Socialise. Drink a little bit. And have a passion for at least something. Get outside in the sun every day.
Eat well. Regardless of whether you're carnivore or vegan, avoid processed foods. Cut out sugar, refined carbohydrates (flour) and industrial seed-oils (PUFA's) - note that most junk food is primarily made from these three cheap and deadly ingredients. Eat good fats, mono and saturated, fish and eggs, butter, etc. The body desperately needs fats and cholesterol, your brain and cell membranes are made of fats. If you're vegan, please supplement for the stuff you're missing.
That's it. Simple.
