make changes you can live with forever. I have decided that I'm not going to give up sweets forever. I did that before and lost 35 lbs, but it didn't stay off because giving up sweets is not something I'm willing to do. I'll work out more if I need to, but that's one of the things I'm not willing to live without. I am willing to live with smaller portions, eating more veggies and fruit, cutting out many grains and drinking more water.
You have to find what works for you and be able to live with your changes/choices. Everyone is different. I won't pass up a homemade chocolate chip cookie. I won't eat 10, but if someone makes some I'll eat one.
Just figure out what you can live with forever.