I'm 68, I do 30 min treadmill daily, 10 min rowing 3x/wk, 25 min bike w 7 sets of dumb bells at 3-4 min intervals. I also have 2 sons, athletic who work out (but not overly so). My goal is to lose weight, maintain muscle mass going into old age, keep inflammation down, feel good. Works well for maintaining muscle mass and feeling good, not so much for weight loss (I'm about BMI 27, which penalizes muscles). Not trying to impress anyone, just trying to be healthy and keep up w boys on hikes.
You are right in that the challenge is to not overdo and get injured. I've never had back or knee problems, but had 3rd hernia surgery in '19 (Ha! It seems we eventually injure either our back or front). Lately, I felt a strain in lower abdomen, gave up the lifting for swimming, although I hope to go back to the lifting. My sets are 15x ea shoulder press, curls, chest press. I suspect the curls are cause of strain, not sure. Rowing taxes my lower back, but I get over it. Swimming the gold standard for exercise wo injury.
My hero is Jack LaLanne:
