Okay, so this isn't as great as the "prosaic" comment in the last post by Jill, but here is an idea for any and all of you hoping for some inspiration or support when you're struggling with writer's block or self-esteem as a writer.
While this is not something I've personally done, I have done similar things for others. It is completely up to you what way you do it, find some inner creativity in that regard.
Take a blank sheet of paper on a good day and write down some words of encouragement. Pretend they are for someone else; technically, they are. They're for the you who will occasionally need a pick me up. If you want to have lots of them, ask some of your colleagues and friends to join; you don't have to admit they're for you if you don't want to.
Cut the paper so each quote now is a strip of paper. You may fold this in half and put in a box or jar, or if you like this, you could put them on a tackboard next to where you work. If you want you could throw up some quotes from the site Jill suggested or from the multitude of books and websites you have read. Whatever could work for you.
There you go. The cliched saying says "a picture is worth a thousand words," so let those words paint a picture of reality in your head: you can do it; you're a great person in lots of ways; and you know how to work that pen or keyboard in magical ways.
Good luck and sometimes the best support group is yourself. You might be "your own worst enemy" or your harshest critic, but if you detach yourself from the self-imposed restraints, your mind and your craft will be freer than dwelling permits.
P.S. A variation of this that I'm doing right now is using the guise of writing fortune cookie sayings for co-workers. They don't know but they'll get a mini takeout box (craft stores have EVERYTHING!), a fortune cookie, some candy, and all the fortune sayings the group wrote at training. The key is to motivate, whether yourself or another person, and hopefully, this will work. I will acknowledge the icebreaker of writing a fortune cookie expression is something I found online, but I let my mind run loose with this...maybe overboard too, but it was fun nonetheless. I hope you can find some fun in doing something (nice) like this for yourself! Let us know how it works too.