Yes, I Suck: Self-Help Through Negative Thinking
time.com
time.com
You might think, "this cruise isn't as fun as I thought it would be." Which can either lead you to think "this sucks" or "maybe if I take this elevator below the passenger decks, hey a ping pong table... why are their Mexicans lined up along the wall... maybe I should go back up." (sorry, I have a better example from when I used to be a bit depressive, but I can't remember it.)
Also, I expect that what works has a lot to do with the personality type you match.
[addendum: It's as the guy who moved to speak to a new person every day for thirty days. I doubt he tells himself he sucks at talking to girls. More likely he recognizes the fear, chooses it is something he wants to do, and speaks. (Boy that can be hard.) Huh, I'm struggling to point out the article title and hooks betray none of the nuance.]
So the thing is to tell yourself you suck - having in mind, that at least you know you do. Because most people don't.
http://www.manageangerdaily.com/mad-blog/the-pitfalls-of-pos...
As an observation (and whether or not it's right), we tend to view the world in terms of people who 'are' great or people who 'suck at' things, if you see what I mean. As such, "I'm so great - why can't I write this parser" becomes a much less helpful notion than "I suck at writing parsers" because the former implies failure whereas the latter implies a much greater scope for improvement.
I admit that it's all a bit hand-wavey, but by and large I find that my positive thoughts tend to be general ("Ain't life grand?", "Man, this world is awesome") whereas the negatives often settle on specifics ("My handwriting is embarrassing!", "I don't comment my code nearly enough") - I think we can all agree that knowing specifically where things are going wrong is far more useful than knowing were they're going right in general.