I'm not sure it's that simple. If you have weak back muscles, for example, walking is not going to do that much for them - but weight lifting will. If your qu

I'm not sure it's that simple. If you have weak back muscles, for example, walking is not going to do that much for them - but weight lifting will. If your quads have atrophied because of a past knee injury, just walking - even very actively - will not fix them (bitter experience here) and the injury may well recur. But gentle goblet squats and light leg presses combined with balance exercises for proprioception will sort that out. You lose a lot of muscle when you get older, and if you have any injuries you will naturally tend to avoid specific movements in your daily life. This _is_ better addressed by weight training (ideally with physio guidence) rather than just aiming for a goal of "being active".