Agree with Sagewing here mate, you do sound like you have a lot of doubt, is that with your ability? I’m guessing you’re an older chap? Maybe thinking this is a young man’s game? Am I right? Got to be honest with yourself. Only you hold the answers. Just drill yourself with questions. Write it down, follow the questions, question all your answers. Ask your self why…
LOL!!! You just might have a point! 
I think when they spend more time on Sitepoint discussing whether they should quit than they do discussing web design, it may be time to make a change.
I have days when any or all of the above are true. I think that just goes with the territory.
Still every day I wake up, I can’t think of anything I’d rather do, than what I do. That’s what keeps me in the saddle. The day I wake up and think,“I’d rather be working at WalMart… I’ll go apply.”