It starts with a leap of faith, reminds me of roller coasterm getting started-you know it will bring you up and down.  And you believe you can do it.  Think big. Start small.  

Say your goal outloud to someone you know. Say it again in a week to remind yourself.  Post it on social media so others have read it.  Even if they may not care nor remember--it makes me, the one who posts it, feel more accountable. 

Anticipate a slip and manage it. i.e. my healthy habit for 2017 is to not worry after 5:00 PM. So if I do, and I know I will for the first part at least, I've said I will write my worry down.  So I know I won't rid my habit (worrying about something at night) but I will try to get out of the habit by becoming aware, writing it down, and slowly, help me to let the worry, and the habit, go