The first rejection letter I received came on the same day I was told I could never have kids. Somehow it just didn't seem all that important and was thrown somewhere I can't find. Then I joined RWA and submitted to an e-publisher that, during the year they had the manuscript, changed into a place I didn't buy books from anymore. I didn't mind getting the rejection letter.
After that, I won a contest at TWRP and got a most wonderful editor, so I submitted the story previously submitted to the other publisher and got a rejection. I was really bummed. Until I re-read the story. Then I was really embarrassed. When I had sent that novel off years ago, I thought it looked really good. Really good. But as the years passed, my technique improved and now the story was bad. B-A-D. As my editor said: I really wanted to kill the hero. She had a point. I wanted to kill him too. So, guess what? I did. :) Kept his name and occupation and tried really hard to clean him up since my editor said she'd look at another round. It still got rejected. I was really bummed, but asked if I could try again. Poor editor. She really needs a medal. Third time was a charm, and I'm happy to say my completely reworked story, with a new and improved hero, is coming out in August. :)
My advice is to not let rejections get you down. Everyone gets them. It's what you do with them that counts. And if you have a manuscript sitting around that you haven't read for awhile: read it before sending it out. Just saying.