First: At the beginning of the formation of a new habit, put force and enthusiasm into your expression. Remember that you are taking the first steps toward making the new mental path and that it is much harder at first than it will be afterwards. Make the path as clear and as deep as you can at the beginning, so that you can readily see it the next time you wish to follow it.
Second: Keep your attention firmly concentrated on the new path building, and keep your mind away from the old paths, lest you incline toward them. Forget all about the old paths, and concern yourself only with the new ones that you are building to order.
Third: Travel over your newly made paths as often as possible. Make opportunities for doing so, without waiting for them to arise through luck or chance. The oftener you go over the new paths, the sooner will they become well worn and easily traveled. Create plans for passing over these new habit paths at the very start.
Fourth: Be sure that you have mapped out the right path as your definite chief aim, and then go ahead without fear and without allowing yourself to doubt. “Place your hand upon the plow, and look not backward.” Select your goal, then make good, deep, wide mental paths leading straight to it.
Source: Your Millionaire Mindset by Don Green