Want to get back into my Marine Corps shape

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Hey there everyone, my name is Greg, and I am once again taking another stab at getting my butt back in shape. I have been here before a few times and failed miserably. I would get on the bandwagon, and would fall back off at the end of a week or so. I want to say that this time, I am here to stay.
A few weeks ago, I was cleaning up stuff in my basement and pulled out my old Marine Corps Uniforms. I sat there staring at my Dress Blues that I have not fit into since I got out back in 2008. Since then, I quit running and working out and flat out got lazy. I got out of the Corps at 205 lbs, and the day I pulled out my uniforms and made up my mind to get back on track I looked down at the scales...269 pounds. That moment, I put my foot down and said I WILL NOT see the scale hit 270.
So, the last few weeks, I have changed up my diet and have been eating healthy, and I have been walking between 3-5 miles every other day. My goal is to fit back into my blues, and eventually, to BEAT my last Marine Corps physical fitness test score which was a 24 minute 3 mile run, 100 crunches in two minutes and 15 pull ups.
As of today, I am now 18 lbs down from my start weight! My first goal is to see 20 lbs come off, as I have never lost that much weight before. I am counting on MFP to help make that happen!