Most studies show it takes anywhere from 20-30 days to begin a new habit. I have another theory. I don't think there are really a magic number of days, as much as there are a number of walls that we hit.
1. Wall #1. The easy route.
This is when you get your first opportunity to not follow through on your new habit. So you started jogging and now you have a rainy day. Or you have been eating right and now is the day you see that caramel chocolate cream cheesecake on the desert special. I would say people fall 50/50 on this one. It's not a deal breaker if you don't make it past this wall to a new habit, but if you did not succeed this time you will have to jump it soon.
2. Wall#2. Terra Nova Scotia.
This is the wall that you hit right after you have crossed the border into new territory. Let me explain a little further. So you actually went further than you ever have before at achieving your goal. You make it 20+ days on your new workout routine. Or you actually read the first 15 books of the bible on your "read through the bible in a year" plan. You think to yourself, "Wow. I have never been this far before, Maybe I deserve a break?" Au Contraire mon fraire! Don't be fooled! Just because you have been further than you ever have before, doesn't mean you have yet established the habit, . This is the place where you must reaffirm your goals and push through.
3. Wall #3. Exiting the Atmosphere.
This is the wall of walls. This is where you are almost to the point of making a habit with your one final test ahead of you. (This sometimes gets split up into phase 1 and phase 2 but for brevity's sake we'll stay at one wall) This is the wall that rattles you to the core and ends up either in a disaster;reset or a phoenix uprising;rebirth. This is the one that keeps you up at night. You are not sure if you can make this a real habit or just a "phase" in your life. Many people never get over this wall until someone close to them dies, or unless they suffer a life threatening illness (sorry to get all morbid for a second) this is where all hell breaks loose to try to shake you off of your path. But if you hold on with all you got and weather the storm like Lt. Dan in Forrest Gump, you will find yourself on the other side with a newly formed habit and a story to tell about.
I just wanted to write this as an encouragement, because I know there are some of you out there that are on the right path and are one wall away from getting the next great thing started in your life. You can do this, trust God, work hard, and move one step at a time!