Stephen McCranie made a fabulous comic encouraging people to be friends with failure. This is my favorite panel:

Image Source: http://doodlealley.com/2012/10/10/be-…

His comic also reminds me of this apocryphal tale my adviser has told me more times than I can count. The story goes that a ceramics prof divided his class into two groups: one group was graded based on quantity (how many pounds of pots they made) and the other on quality (one magical final pot). The quantity group ended up having better work, 'cause practice.