In remarking upon this, Mr. Stevenson spoke of an interaction he had with Rosa Parks, which was particularly inspiring to him. He explained that when he met Ms. Parks, and explained to her what he did, she told him that he must be "tired" but that he must find a way to re-energize himself.
That's his message in a nutshell, but the true value of the message is in listening to him speak it.
I couldn't embed the video correctly (yet, I'm still working on it) so all I have so far is a link to the ceremonies. Mr. Stevenson's remarks begin about 1/3 of the way in. So, without further ado, congrats to the Class of 2008, and I hope you enjoy Mr. Stevenson.