Why am I so susceptible to getting myself in over my head?

It seems I no matter how ridiculous a challenge is, I just keep jumping in head first! Is there some sort of disorder that causes this? Is it treatable, or am I doomed to a life of spontaneous commitment and resulting torture? Last year it was the triathlon that turned into TWO triathlons, which has turned into FOUR triathlons this year. One of these triathlons is scheduled to be an Olympic distance one. EEEK! In all my wisdom, I figured that these FOUR freaking triathlons would be much easier to do, if I didn’t have to lug all my extraneous weight around while training. Logical conclusion? Yes.

You might be thinking that the FOUR triathlons is where I got in over my head, but you are wrong.

To make a long story short, a co worker and I made a weight loss bet. Over lunch one day, we discovered we weigh exactly the same and both wanted to drop some of it. A week later we signed the contract for the bet. We have till March 31st to reach a certain weight. There is about $150 in prizes at stake for this bet. Now, allow me to tell you a bit about the guy I have to beat. He is two inches taller than me and massively muscular. He is also 18 years older than me (which I suspect is all I have going for me). The weight we are trying to reach by March 31st is also his target weight. My target weight would still be about 1000 lbs less than even that. He also spent a good portion of his life as a personal trainer. Ugh. Wish me luck!