What's the best way to change my eating habits for good?

I should start out by saying that I've always been a very active person up until about 3 years ago. When I was in highschool I raced dirtbikes and played tons of sports. I was under 100lbs till my senior year when I "grew up" and weighed 135, which I respectably say that was my ideal weight. I was still very active and ate healthy. My only problem was my very active and large appetite. Which back then was ok, because I was active. So, I got hurt one year, got on birth control, and started a job where I sat on my butt 8 hours a day. I gained 40lbs in 2 months. Now I am up to 180 since then. My problem being, my large appetite never went away. Recently I've started to exercise regularly, and I'm also trying to diet and eat healthy. But since I've been exercising, my appetite is getting larger and I'm wanting to consume more carbs and calories since I'm burning them off. My question is, how do I fight the cravings and temptations gorge down an entire cow? I can't afford any specialty shakes or smoothies from the diet companies, half the time they don't work anyways. I want to be the healthy, active me again. What should I do?