I recently read that it takes 66 days to establish a new habit--in other words, doing something over and over enough times that you have changed your brain's neuro-pathways to the point that the new activity becomes something you do without thinking about it.
I have no new habits I'm trying to take up, but I have a few I'm trying to let go of, like not exercising enough, still eating too much, not spending enough time focused on myself.
Giving up old habits takes the same amount of time, only the process is in reverse: you have to let established neuro-pathways atrophy.
So it is that I am four days in to giving up some of those old ways. I'll check back in in 62 days to let you know how it's going.