Gotta get my pack back on

Hey everyone, just introducing myself. I'm Jamie, I got out of the Corps back in 2008 and have put on about 100 pounds since then. I am now 301 lbs. I started back on track 6 days ago, and I hope to be down to 250 within 6 months. I really don't know why I let myself get like this. It has really dragged down my self esteem, and people have a hard time believing that I was ever a Marine if the topic comes up. I am working with a 1000 calorie deficit, and plan on incorporating exercise into my plan when I lose the first 25 lbs. So far this week hasn't been bad at all, I don't often feel hungry, and I am amazed at how much food a guy has to eat to maintain 300 lbs.
I stated studying accounting back in August and hope to get my degree within 4 years, and I know from experience how much a person's image comes into play for various life opportunities, i.e. careers. So, basically, aside from general health and self-image improvements, I am doing this to improve my chances at getting a decent job after I graduate. I don't want to be stuck working on drilling rigs the rest of my life, which basically has been the case since I EAS'd. That is an incredibly unhealthy lifestyle.
Wish me luck guys, a year and a half is my goal for 100 lbs lost, and it's just around the corner.