If you asked my wife, she'd tell you my mood fluctuates up and down with my writing . If the words flow easily, I'm up. On a day when the right words escape me, I'm down. The same can be said about acceptances or rejections, and good reviews or the inevitable (but thankfully rare) bad review.
Then there's contests. Let's be honest--there's a certain arbitrariness about book contests. Tastes in book are