There are a lot of reasons why, at ANY age, making sure you have enough muscle is very important indeed.
And they are not just the obvious reasons (e.g. helping the spine and joints cope better, coping with stress and so on).
But you don't need to look like the guy above.
A recent study shows how having enough actual muscle may help our health - in particular, may make it a lot less likely you will develop type 2 diabetes.