That's the straw that broke the camel's back for you, huh? Yeah, it's a shitty feeling. I remember what did it for me: I went for a jog for the first time in my life at 17. Yes, the first time ever. I had been active by dancing Romanian folk for a decade yet I still remained extremely overweight, at 245lbs, as previously stated, but I had never actually jogged for exercise before. It was when I could barely breathe after doing one lap around my apartment complex, the equivalent of .10 miles, that I realized I had to get my shit together. So I ran and walked a combination of 5 miles almost every other day for two months and lost 45 pounds.
I had gained it again several years later and went back to 220, but I brought it down from that two years ago. Now I've been in the 180s for over a year and I will NEVER let it happen again. It brings on depression and generally makes me lazy.