Celebrate little victories: You deserve it! Just make sure the rewards don't work against your goal (i.e, eating a bowl of ice cream after every salad). Think of a way you can treat yourself, maybe get a smoothie maker or fitness tracker (now that all your friends have one). It's a positive reward that will actually help make a healthier, happier you.
Don't give up so easily: Too often people throw in the towel on resolutions because of one slip up. So what, you had a moment of weakness and ate a cheeseburger. It happens! If weight loss were that easy, it wouldn't be the number one resolution, year after year. Often, we use small slip-ups as an excuse to give up on big goals. Forgive yourself, move on and keep trying.