I was fat at one point, most recently as August of last year. I saw a picture of myself from a wedding, and realized that I needed to lose some weight.
I changed overnight. I threw away all of the junk food in the house, stopped eating fast food, stopped frying food at home, gave up beer, started drinking 1 to 2 gallons of water a day, started taking my lunch to work everyday, and started working out six days a week.
I didn't spend as much money because it was cheaper to take my lunch, I don't have a gym membership (running is free, so is walking, so are pushups, etc.). I also quit smoking after about 10 years of combined smoking, dipping, etc.
You can change if you want to. It's not easy, but if you want to do it, you can do it.