Obviously, I've Completely Lost My Mind

It started with trying to impress my trainer and reclaiming some of the ground I lost in the past three years. I decided to do a 5K in November. I was actually still in the "mulling it over" stage, when Hubby emailed me about a nearby half marathon he is doing in February. He invited me to do it with him. I skipped the lol and politely declined, offering instead to be there to cheer him on and give him some tlc at the end.
Now, normally, it would have ended right there. However, while making small talk with my trainer the next day, I happened to mention it. Well, in an instant, he was all over the idea of me doing this race. His enthusiasm was a bit overwhelming at first, and I still wasn't totally sold. Then I compounded my mistake by telling hubby what trainer said. Well, he was so excited and enthusiastic at the mere thought of me doing this race, that I let myself get caught up in the moment and told him to sign me up.
Since then, my newly motivated trainer has been developing my training plan and my hubby just bought me a racing shirt that says, "if found on the ground, please drag my body across the finish line" or something like that, and a magnet for the car that says "13.1 because I'm only half crazy". Oy. What have I done?