Somewhere Between Ambitious and Crazy

So I have been having an internal struggle for a while now and have just come to a decision and was hoping you all could tell me where exactly I fit...am I ambitious or crazy. You see there is a mini-marathon (13.1 miles) here that is part of the festivities for the Indy 500 race and each year some of the dental students run it. When we first moved here I thought they were crazy and then I started thinking maybe they were just ambitious. Well, this year I started to catch the fever! It wasn't quite as bad as it could be as I told myself that I would maybe run it next year since it will be our last year in Indy. However, some of my friends signed up and the fever has gotten worse and worse. Recently I started thinking that maybe I would put an add on Craig's list and try to buy someone's registration since the event sold out in November. The race is getting closer and I considered that I might just be wishing I had signed up just because it is somewhat impossible now. Most people have been training since January and I would be really behind and remember the event is sold out. So I mentioned that I was considering Craig's list to a friend and be careful what you wish for because later that day I got a call from another friend who had signed up saying she had to have surgery and was looking for someone to buy her registration. Now I have to make a real decision. Do I do it now when I have the chance even though I will be behind in my training or do I wait for next year and see if this temporary burst of insanity goes away? I need help...is it ambition I am feeling or just simple craziness. Tell me what you think.