I’m 69. Recently retired as a fitness trainer. I do a full body workout twice a week. Works for me.
Balance is important too. I had read that having good balance was important for fall prevention and the recommendation was to practice standing on one leg (alternating legs). I started doing that when I was waiting for my tea to reheat in the microwave, standing in line, etc.
I think my improved balance has save me a few times. A neighbor doesn’t allow shoes in his home. There were two steps down into another room. A nail was sticking up a bit on a metal edge piece at the top of the stairs and my sock caught on it. I thought I was going to land on my face but I managed to land upright albeit with a torn sock and a couple sore and bruised toes.
I’m the same age.
I break the resistance training into three days through the week: Chest/Triceps...Biceps/Back...Legs and Deadlifts.
I’m often still a little sore by the time they roll around again the following week. So I lighten the overall load for that week, but still do the work.
You prefer lighter, full body workouts 2x week?
At 81 I still play pickup basketball 2-3 times a week. Slowing down some but set a lot of screens/picks and look to get assists. Shooting smarter, too.
In my 30s, 40s and into my 50s I was a semi-serious runner, training regularly and racing frequently. Then a mild arthritis in the left knee caused the repetitive motion to become too painful. The b’ball doesn’t hurt unless I overdo it- a fourth session in a week will have it complaining.