Practice holding to your habit.
That way, if you mess up, you can say to yourself "Oh well, it was only practice. I should get back to practicing without worrying about that mistake."
The key is to remember that
everything that we do is practice... Even our big performances where we won't get a second chance if we mess up are only practice for the next big performance without a second chance.
There are millions of distractions in the world, and if we're not in the mindset of all of our actions simply being practice, then falling for a distraction could be a major set-back, because we feel like we failed. We can't fail at practicing, as long as we practice again, so there are no major set-backs. It takes practice to become a smoker, just as it takes practice to run two miles without walking. It takes practice to sleep in late, just as it takes practice to wake up early each morning. We can not fail to practice, but we can make a conscious decision about what we want to practice.
It also takes a lot less willpower to practice, but the results are the same as if we had forced ourselves to do those tasks. Instead of using brute force and willpower, tiring ourselves out mentally, it's a lot easier to use psychological leverage, such as always practicing, using positive thinking, or just plain taking a placebo.
