Discussions

So slowly almost too the point where I didnt notice it, One of my dogs has been slowing down.. just that little bit. Mornings when he used to get out of bed when myself and the other dog did, he would usually be the first to the door to be let out.  
Lately I have noticed that he stays in bed now till sometimes 2 hours after we get up. He sleeps (quite comfortably) on his bed, and when I ask him if he wants to go out, he just ignores me lol.  
 
This will be only the second dog I have had to grow too "retirement years".. (sadly due to a divorce and moving I had to re-home my other dog at 8 years old). I guess what Im curious about is when do they start slowing down and taking it easy?