Others have suggested baby steps; I'm going to go out on a little bit of a limb and say that it's sometimes easier to make all your necessary changes at once. For some people, making a small change each week or month has led to big transformative changes over time, so it's certainly one possibility--but so is just jumping in there.
Little changes didn't work for me because I invariably wanted to do/eat the very thing I said I would no longer do/eat, as I was focused on it. I felt like I was hacking away at my lifestyle with nothing to fill the holes I left. This time, I instead made one concerted push and it's working for me.
What made this different is that everything I was doing, I saw as an addition, not a subtraction. I added exercise, whole grain foods, fruit, vegetables, home-cooked meals. (That happened to coincide with subtracting stuff, but I was so focused on the additions that I didn't see the subtractions as much.)
You don't suck and you're neither lazy nor stupid. You just haven't quite found the thing that will pry you out of your comfortable rut and plop you down in the weight-loss groove instead. Trust me, I'm an
incredibly lazy person, yet I haven't strayed from my plan once because it's now become my "new normal." I formed a new, more health-conscious rut, you could say. I used my laziness and inertia to my own benefit.
I'm 41. It took me so many years to find out what works for me. Keep looking; you'll find what works for you. There are so many paths to losing weight and better health that one of them has to be your perfect way. Just focus on that and not on feeling miserable for yesterday. The mistakes you made then are just learning experiences for today.