Strength!

As we age we lose muscle. That is a fact that is hard to face as you get into your later 40's you still work out but don't see the results that you did years ago. This is frustrating and requires a different mind-set. You should aim to be as STRONG and HEALTHY as you can, and to retain as much muscle and bone density as you are able.
If you look at older strength trained people they almost all look younger due to their more erect frame, tighter torso and better range of movement.
This is where it's at for all of us. Stay harder, tighter, but most of all feel better. There are no shortcuts, and it will take work to stay that way.
In this linked article, much older and frail individuals were able to gain muscle and strength when using resistance training. Don't get frail!! Start now while you can make the most of it.

Stay strong...live long!