because i said so

Nothing makes me more determined to do something than being told that I can't do it. Particularly when someone says I am not dedicated or disciplined enough. Today someone told me that he doesn't think I can be ready to do the Avon Walk in April, let alone lose 25 lbs by then. So, of course, I upped my own stakes. So now I have to get a 6 pack on my stomach, work out every day, plus go to yoga once a week, run extra for the big walk, and lose 25 lbs. By the end of February.
I can do it, because I said so. And because he said that I can't.