Talk to Yourself... Nicely
Self-talk really does work, whether it is positive or negative. Lift your spirits and prolong your motivation every single day by telling yourself that you can and will succeed.
You may even find that it is helpful to say self-affirming phrases out loud. Your roommates may think you've gone crazy, but when you find it is quite effective, you won't mind.
Look in the mirror today, and say, "Nothing is going to stop me from meeting my weight loss goal."