I am 65 years old, and I started about six months ago. I usually do five 3-minute intervals, 3 times a week, with the heart rate in the 135-150 range.
I think I feel better, or at least no worse.
Run 3 miles every other day. If you can’t because of leg, knee issues, take up swimming or bike riding. High aerobic exercise where you get your heart and lungs working as if you are chasing game while hunting is the way to think. The body we have today is a body built to benefit hunter gatherers. When you do high aerobic exercise your body starts relating that to survival and ALL of your senses improve 20 fold. Hearing, sight, smell. I use to be 100 pounds overweight and it really blew my mind how much it shut those senses down. 3 minutes intervals will not benefit you at all. You have to run for half an hour non stop. Get to that point.
I’m 75, walk 5-10 miles a day with a 30lb pack.
btt