I know that this thread is older, but in the event that anyone reads it, I thought I might comment (as I have struggled at one point with this)

I believe it takes over a month (7 weeks?) to create a habit. Can't remember - try google-ing

It is hard. Our brain doesn't have the information for the new habit. You have to practise it more and more until the networks build and form relationships. However, it it takes TIME (over a month of consistent action) & PERSEVERANCE.

Our brain resists change because the familiar is comfortable. New (including habit) is perceived as threatening - it stays "safe" (for our well being). This may be evolutionary, like so many other things we struggle with today (reptilian brain etc) ...