Advice on breaking/making habits

I came across a posting on brainpickings.org about William James' treatise "Habit". Some of the quotations are very apt for the situation I (and I imagine many others on this site) are in. Here are a few.

Never suffer an exception to occur till the new habit is securely rooted in your life. Each lapse is like the letting fall of a ball of string which one is carefully winding up; a single slip undoes more than a great many turns will wind again. Continuity of training is the great means of making the nervous system act infallibly right … It is surprising how soon a desire will die of inanition if it be never fed.​

and

Just as, if we let our emotions evaporate, they get into a way of evaporating; so there is reason to suppose that if we often flinch from making an effort, before we know it the effort-making capacity will be gone; and that, if we suffer the wandering of our attention, presently it will wander all the time. Attention and effort are … but two names for the same psychic fact.​

The complete book is available here and the brainpickings article is at http://www.brainpickings.org/index.php/2012/09/25/william-james-on-habit/