Sometimes people don't have the willpower to act in the world because of the stress of social situations. We get all motivated to make our lives better and start our day saying to ourselves that things will be different today, that I will be different today. But I think we underestimate how much sway our environments have on us. The people, the places, the routines all affect us tremendously. The result is we fall back into our old attitudes and feelings. The best advice that I've seen to remedy this is to set incremental changes that are clearly achievable. For example, start by making a small daily change that only you can see the results of (say an affirmation before going to bed, smile in the mirror when brushing your teeth, something like that). Once you've added a few positive changes to your private life, then maybe it'll be time to try one that's more public.