Ya, that is always the hard part. Accountability is usually a necessary thing to overcome dedication/commitment problems, and it can be hard to be accountable to yourself. The good news it’s never too late to start making changes.
My father has been obese as far back as I can remember (450+ kind of obese), he is nearly sixty and recently got diagnosed with type 2 diabetes. He has the worst eating habits and commitment to health of almost anyone I have ever met. It took a scare where his diabetes was beginning to compromise his eyesight for him to want to change, but he has actually started to make changes. He is loosing the weight quickly and his blood sugar is under control again.
I don’t know your situation, but if he can do it I’m sure you can too! Not to underplay how tough it is to make those kind of changes, just maybe reminding you that you have the power and the will somewhere inside to make the change. :)