Milton Glaser said this quote

If you can sustain your interest in what you’re doing, you’re an extremely fortunate person. What you see very frequently in people’s professional lives, and perhaps in their emotional life as well, is that they lose interest in the third act. You sort of get tired, and indifferent, and, sometimes, defensive. And you kind of lose your capacity for astonishment — and that’s a great loss, because the world is a very astonishing place. What I feel fortunate about is that I’m still astonished, that things still amaze me. And I think that that’s the great benefit of being in the arts, where the possibility for learning never disappears, where you basically have to admit you never learn it.