Just some anecdata here, but I was toeing the line between overweight and obese about a year ago. I read David Goggins book Can't Hurt Me, and one of the things he talked about was having a note in the mirror reminding you of your goals (real novel concept ikr?). Anyways, the way he phrased it was something like, "If you're fat and don't want to be, right down the raw truth on that note and read it every morning, then write down how you'll fix it". I wrote something along those lines down, and read it every morning. The guilt and shame I felt from allowing myself to slip up this bad definitely helped motivate me.

1 year later, and I'm down 35 pounds with another 10-20 to go. I feel great! walking doesn't hurt anymore, doing physical stuff is fun again, and I have more energy than I used to. All that to say, the guilt and shame definitely helped motivate me, but YMMV :)