One of the best things about returning to school, has been the challenge of it all. When I pick my own projects, they tend to be challenging, but I never really hit a wall.
In my grad school classes, however, I'm always hitting a wall. That seems to be the whole point, sometimes. And it hurts. But somehow my fellow students and I get past the walls, and we look back and wonder at how small they really are from the other side.