Asking myself, "What do you want to create?" before going to an important meeting, event, or date. This habit is really life changing and puts you in the director's chair in life. It allows you to stop and think about the purpose of participating in that event, with those particular people, and creates an urgency to think about the reason for it.
Any long-term behavioral change, including weight loss, is going to test our limits, challenge our beliefs, make us face our self-doubts, and be an amazing opportunity to live by our resilience and strength. Altering your mindset about this entire process will help you adjust expectations and be able to take setbacks in stride (or at least make them a little less toxic).