I have an interest in muscles and exercise. It's just a personal interest, but I try to put what I learn about muscles to practical use. It's interesting that most men develop more muscle mass than women because of the level of testosterone. Yet women can train and become very strong and not have bulging muscles.
I've also learned that it's really true that you lose it if you don't use it. And it doesn't take long for your muscles to start to atrophy, if you become inactive.
Many trainers believe that you should weight train, maybe three times a week, and rest your muscles in between sessions. This works well to develop muscles without over-doing.
If you look back at our ancient ancestors, they were always on the move, using all their muscles. Our bodies weren't meant to be couch potatoes.