Day 1 of pre-training

I started my pretraining for the 1/2 marathon today. I did 2.154 miles in 30 minutes on the treadmill and burned 367 calories. I talked to the personal trainer at the gym and he recommended that I talk to my asthma doctor before I get serious. He also said I should be working on endurance and going to the gym at least five days a week right now. My goal is to be at 180 before the end of January. That is about 5 lbs. away.