Why?

We've officially entered the "why" phase of Corbin's life.  A phase we knew was going to come, but honestly, we aren't ready.  This afternoon, we decided to take advantage of the nice weather and take a walk around the neighborhood.  We crossed paths with a very nice couple (probably a neighbor we still don't know) walking thier dog.  Corbin was thrilled when they stopped to let him pet thier dog.  Then they were on thier way.  Our conversation went like this:

Corbin - "Where are they going?"
Me - "Continuing thier walk."
Corbin - "Why?"
Me - "Because it's good excercise."
Corbin - "Why"
Me - "Because we all need excercise to stay healthy."
Corbin - "Why?"
Me - "So we live a long time."
Corbin  - "Why?"
Me - "Just because.
Corbin - "Why just because?"
I had no answer.....and I swore I wouldn't crush his curiousity by answering "because."  But, I did it.  Yet another thing I swore I wouldn't do as a parent and then did.