[davey48016]

Rock climbing is probably going to be just as good at weight lifting. My understanding of the mental model here is:

Up until around age 60, your body adjusts your muscle mass based on usage. Somewhere around 60, you start losing muscle mass. If you have just enough muscle for day to day activities in a sedentary life at that point, then over time daily tasks like carrying groceries or standing up out of a chair are going to become prohibitively difficult. You need to do something that encourages your body to grow more muscle than you need for day to day life so that you can afford to lose some of it.