I find that sometimes to motivate myself I get a me versus them thing going on in my mind. When I get rejected from a gallery I fight back by thinking they are wrong, and I am going to prove that by making more photographs my way and getting a show some place else! The rejection becomes a burr in my saddle that spurs me on to make more work, my way.
I also tend to do this in my club groups. If I feel that my work is being mistreated or threatened I tend to use this as inspiration to make new work.
This overreacting might be a natural way that I continue to grow and challenge myself (or it could mean I am a JERK!, lets go with the growing artist thingy, it sounds better). Sometimes it might annoy people I am around when I overreact but I believe the end justifies the means in this case!