A friend just shared this with me:
"I believe that work of excellence is transformational. Once a student see that he or she is capable of excellence, that student is never quite the same. There is a new self-image, a new notion of possibility. There is an appetite for excellence After students have had a taste of excellence, they're never quite satisfied with less; they're always hungry." --Ron Berger
I think doing something excellent is the most transformational, but seeing others doing things excellently is also beneficial. I love the positive classroom format in Vanguard that allows for that. I've had experiences myself during class seeing another's great work (usually one of the students!) and thought, "I could do that too if I put my mind to it."
(I looked up Ron Berger - he wrote a book called "An Ethic of Excellence." The reviews are good, looks like I need to add it to my ever-growing "to-read" list.)