One thing that helped me when I'd start to freak out / get overwhelmed about it all:
When I'd look in the mirror, still seeing the obvious of how far I had to go, I'd tell myself, "I'm not where I want to be YET, but I'm getting there! I'm getting there!!"
Silly, perhaps, but it was enough of a pep talk to get me over the edge and keep it going.
Don't focus on how *lucky* you imagine those other skinny people to be. Trust me, they have their own issues. Weight gain may or may not be one of them NOW, but we all have things we struggle with.
Lastly, time is going to march on, regardless of whether you develop a healthy lifestyle or not! A week from now...six months from now....a year from now....what do you want to be: fatter, thinner or the same? Act accordingly.
You'll get there if you don't quit - I promise!! You don't lose weight to get healthy; you develop a healthy lifestyle and the weight comes off (took me forever to figure that one out!).