It’s often said that it’s mind over matter.
This goes for dieting.
If you can believe in yourself, believe that you really can lose weight, and apply yourself to it, then you will.
Think positive about the whole thing. Don’t be defeatist. Don’t tell yourself that you’re an overweight slob that’s never going to lose weight. Instead look in the mirror, and tell yourself how much better you will look (to yourself and others) when you do shed those pounds. Tell yourself how much better you will feel.
You don’t have to eat everything on your plate. If you find yourself wasting food, and can’t afford it, or feel guilty about such a practice, then order smaller portions when you eat out, and cook less at home, or split portions in two where practical for another meal another day, and freeze it.
You don’t have to eat every time you do anything. It’s perfectly fine to go to a movie without a 32 ounce soda, and a large popcorn. If you’ve eaten before you went into the theatre, and you’re going to eat again when you leave or get home, you’ll survive quite well without those extra calories! Also think how much money you save each time you don’t eat stuff that you really don’t need. You’ll find after a while, you break the habit of heading for the concession stand in any case.