Use it or Lose it?

I have noticed that if I don't have sex or masturbate on a regular basis the frequence and firmness of my erections starts to diminish.  ie..  I'm not getting as hard as often as I used to.  Yes, I know that some of this is caused by my age.  But if I start "exercising my John Thomas" more frequently things seem to 'pick up' (pun intended).  

Anyone else notice this?

Not my picture but I'm starting to get worried I might wind up like this guy.