Impossible Goal–Keeping My Promises to Me

I would like to make keeping my word to me as my 2018 impossible goal. The three areas in my life where I don’t do this is money, food & exercise, and my time. These are the areas where I consistently let myself down. I say I’m going to do one thing and then I don’t follow through. Can keeping my word be my 2018 Impossible Goal? Or does it need to be one of the three areas where I don’t keep my word? And if so, how do I make progress in the other two area when my brain says if I don’t focus on all three areas I still won’t be keeping my word to me in those other areas.