It is amazing when you realize how many muscles we have in our body. I don't think much about it until I end up doing something that causes me to have sore muscles and then I am very aware of it.
Even if I do new work out routine, I find that I will have sore muscles the next day. I use my voluntary skeletal muscles when I work out and concentrate on certain areas that I want to strengthen and tone.
I think keeping our muscles strong is one key to overall well being. It is never too late to begin muscle strength training and once your muscles adjust, you will feel much stronger.