Weight Loss

Ya'll I am trying to lose massive weight (i.e. like 100 lbs. to get where I need to be weight-wise for my height and bone structure). For those of you that have lost a little weight or massive weight, what did ya'll do? how did you stay motivated to exercise and eat the foods you're supposed to eat? How did you not cheat? how did you resist the temptation to eat when you got hungry, say, at 10 pm?