For me, the motivating moment was owning up to how much weight I had put on. There was a time in my life where I was too skinny (imagine that) and then almost overnight (well, three years) I had put on 40 pounds. It amazes me every time I pass by a mirror or buy clothing.
I found it was easy to just pretend it didn't matter, or that I could just lose the weight at any time. But I had a lightbulb moment one day when I saw my weight creep above what I had set as my "can't possibly ever go over, not even when I'm pregnant" weight, and decided I had literally sat on my butt long enough.
I think that is the best and only way to achieve permanent weight loss. So far I have lost 6 pounds, and I honestly think that is just from being honest with myself about
: what I am eating, what I am actively doing and what I am still doing that sets me up for failure.
Good luck, and wish me that too.