Second guessing

I spend forever writing something that I think is brilliant. I labor over it, and the next day as I read over what I wrote, I feel that what I wrote is absolutely terrible. Why is that? Am I the only one who feels this phenomenon? Either way, I feel that I am too critical with my work, and after the pride of what I've written wears off, my insecurity in my work sets in. I become afraid of what others will think about it. That's my biggest flaw in anything I create.