I have the same energy today as I had at 65. I mow my entire mid-sized lawn with a push mower without stopping. Just finished a landscaping project to install 15” wide pebble rock covered edging around the 1600 SF house. This is new house built 15 months ago and the builder did not install roof gutters on any houses here. I thought the water falling from roof would cause erosion, so the pebbles break the falling water nicely. I used no dig edging held down by 8” long nylon spikes. I am 80 years young. My secret of good health is 30 minutes treadmill 6 times every week.
So if you don’t have a tread mill then walking 30 minutes 6 days a week would do likewise I’ll assume.
Not sure what your paced at but one can adjust and increase to keep the heart rate where you want I suspect.
My Grandma (father’s mother) lived to be 98. She was rock solid up until about 96. She was religious about her 30 minute morning walk, 30 minute afternoon walk, tending her small garden, being social, and “stay off the damn couch”.
She had a fall and broke her hip at 96 and never quite recovered. She was a force of Nature her entire life. She passed 10 years ago and is legend in the family. It seems everything is still measured up to her.