Whether you believe in your possibilities or in your limitations, you are always right! Right now, watching Ocean's Twelve, I am watching Tess playing Julia Roberts as herself in order to pull off an impossible heist. She's convinced she can't do it, but apparently the team convinced her, and by the time Bruce Willis surprises her she totally bluffs her way through it!
Still, it is difficult at times to see what the possibilities are, and which limitations are actually illusions. I've seen impossible things happen to me, but can't just simply accept them: my mind needs a possible way in which this could have come about, just to ease itself into acceptance.