At 75 Dad hand dug a water well. At 65 for me walking one hour a day is just fine along with some stretching. I miss my yoga classes but do those at times on YouTube, the classes are kind of pricey.
My aunt took up yoga in her mid -60s, and her health, which wasn’t all that bad, began improving, and she gained strength and balance. She celebrated her 98th birthday not on long ago. I’ve decided that she is a role model for all us “kids”.