Hummingbird Moth

I found this on the road during my lunchtime walk.  It seemed to be having trouble flying, and I didn't want it to be run over by a car, so I encouraged it to walk into my hand.  I was a bit concerned because I thought it was a type of Bumblebee, one that was already flattened at the end.  Then I saw the tail feathers and antenna and realized it was something else entirely.  According to this website, it's a Hummingbird Moth.  However, the one I encountered was hardly flying.