toy poodle & exercise

Question
QUESTION: This is probably a stupid question but is it possible for a toy poodle to get too much exercise? My little poodle loves the backyard and we live on a corner and get quite a bit of traffic. He loves running the length of the fence chasing the cars in fact he has worn a hole in the grass he runs so much and so fast. He is 8 years old and he has only been doing this since February since we moved here. I've noticed though that he is going very gray all of a sudden. He is a black poodle and I'm just worried he is over exerting himself. Is that even possible?
He can't wait to get down in the garden everyday to chase the cars when he gets tired he lays down and has a sleep or a big drink of water. I just want to check this isn't bad for him.
Thanks so much!

ANSWER:  The reason you are seeing the grey is becuase of his age nothing else.  Blacks will grizzle.  He will stop himself when he is tired.  Because he has become so active you may want to up his amount of food or he may drop a lot of weight.  Other than that he is fine.

---------- FOLLOW-UP ----------

QUESTION: Thanks so much Keisha! I always worry about him. I've only had him since December and was worried I'd done something to him!
Something else I meant to ask is how long do they live? I thought it was until about 15 is that right? He is so beautiful I'm hoping to have him around for quite a while!
Thanks so much!!

Answer
You are doing just right.  He is probably having a blast.  Just make sure that he cant actually get to the cars  LOL.
I have seen poodles live up to 22 years.  15-18 is usually typical.  They are very long lived.  Even the standard poodles live to old age for dogs.