I personally think that the best motivation to lose weight is health. I have a lot of health problems due to weight. I've developed diabetes, I have trouble breathing and I have chronic pain in my legs and feet.
What could be a better reason to lose weight than to be healthy? I've realized that health is the foundation for everything. When I had it, I didn't pay attention to it and now that I have bad health, I can't enjoy things as I used to.
I also think about my children and what they would do without me if I were to lose my health completely or die early because of the weight.