1) Keep a To Do List:
Everyone tells you to keep a list of what you need to do, which might seem useless and even boring. There really is something that makes you want to complete your tasks more just get to check them off, though. So, if one of your goals is to go to the gym, then write it down, and when you do it, check it off.
2) Pick a friend to keep you accountable:
Tell your friends about your goals and encourage them to keep you accountable. Have them snap you, text you, or even call you once a day to ask you if you have completed your goal.
3) Keep them realistic:
Keep your goals simple. Pick a goal that you have seen someone do and truly believe you can accomplish. A goal doesn't have to be hard to reach for it to have an impact on your life. Even if you have already committed to a resolution, if you see that it is not realistic you should still change it to be doable for yourself. If your goal is to loose 40 pounds or drink a gallon of water, change it to 20 pounds and half a gallon.