Rejection tends to bring me to tears, but it has the added benefit of driving me to dive into my latest WIP with a renewed enthusiasm, which often borders on frenzied desperation. I tend to feel like I'd better get this next one done and make it really, really good, if the work I'm querying isn't getting anywhere.
A little girl on the team I coach starts crying every time she gets behind in a match (usually a very bad move, as it usually indicates the kid is going to give up, lose focus, etc.) but, through her tears she finishes those matches with a furious focus on the win.
She loves to compete; she hates to lose. We're working on the crying thing. I love to write; I hate to get rejected. I'm working on the crying thing, too. In the meantime, I try to use those setbacks to benefit my writing. In a way, they keep me motivated.