I hear you on the all or nothing. I've dealt with that too. What's helped me:
1) Break it down into mini goals. For example, I want to get to 150. Instead of focusing on the 40+ pounds I want to lose, I'm focusing on getting under 190. Then, I'll focus on 180. Reinforce the minigoals with rewards along the way. Buy some new music or get a manicure.
2) When you find yourself getting into all or nothing thinking. For example, I have a bad tendency to do this with exercise. If I oversleep & don't have time for the full 1.5 hour workout (weights & cardio) I planned, I used to just skip it & sleep in. Instead, I'll go for 30 minutes of cardio (or however much I have time for). It helps keep the routine for exercise (which is my toughest challenge of the whole weight loss equation). For food, if you do give into temptation, try to watch the portions. For example, I like chips & chocolate. I used to have big bags of chips or candybars in my home. Now, I don't keep them around and when I do indulge, I buy the single serving instead. And then there's no temptation to keep eating once I've had a taste like there would be if the food is still there. And half the time, the craving is killed by the thought of having to go out & get it (I'm using my sloth in my favor

).
3) Even though you don't want to buy a whole new wardrobe yet, buy some flattering outfits with a good fit and nice colors. I find that doing that along with things like a flattering haircut, getting my nails done, etc. leads to compliments which help boost my self confidence which make me feel less envious of others.
When I get frustrated with the pace of progress, I remind myself I didn't gain this weight overnight, I'm not going to lose it overnight.