Here's your pep-talk for the day: You are awesome.
You can tell stories no one else can. Your ideas are good, and with a little work, they'll be great. Keep working. Keep writing. Edit one more time before submitting that story. Don't quit.
Rejections? Let me show you how many rejections I've received (and I stopped counting a year ago). Your brain will hurt. Your eyes will dry up and crumble to dust. Those gates are awfully tiny, folks, and editors can only let so many stories inside. Have I squeezed a story or two through the eye of a needle? Maybe. But an awful lot of them are lying dead in the desert.
Agents won't give you the time of day? They have to eat, too. They have to sell the big books, the ones with fat advances because, chances are, most books won't earn out and make royalties. Remember that needle's eye? It just got smaller. Keep trying. Write a new book. Go it alone. Be blood, bold, and resolute. Laugh a siege to scorn...yes, MacDuff killed MacBeth, but the tyrant had a good run, didn't he?
Sour reviews? Puh-leeeze. Everyone has an opinion and the internet lets them amplify it. Water off your back, dear writer. Keep writing. Keep climbing. They win when you quit. Forgive your haters. Move on.
But you're tough, too.
You won't give up.
You've already won.