I'm thinkful for "fake it 'til you make it". Whatever the crazy psychological process(es) it is that allow us to put on a good face and pretend at something and then have our psyches join in later is absurd and completely awesome. I presume there are some people out there who make it without having to just put on a good face and pretend at first at new jobs or projects or roles, but that's rarely so for me.
But at this point, I have great faith in fake it 'til you make it, and, well, it may be crazy, but it works, and it lets me step into new things all the time. Without it, I'd probably still be spending all my time in my room reading. Except, probably without it, most of my favorite books wouldn't have gotten published in the first place, is my guess, so thank goodness for quirky psychological tricks that work in our favor.