One of the most common self-defeating behaviors I have witnessed in the general public is what I call the Postponed Start. If x is your desired habit, the Postponed Start usually takes the form of the following statement: "I'll start doing x after y happens". For example:
And so on, and so on.
The unfortunate reality is, though, that we are extremely ineffective at fulfilling promises to ourselves of the above form. Inevitably, y will occur. Our beneficial habit, however, rarely follows. The vast majority of the time, we either a) push back y so that it is now some other, later event, or b) start saying that x was never a priority in the first place (rationalization).
I do this all the time. Before I went on a trip to Europe in May, I had statements of the form 'I will start exercising at 7:00am in the morning when I begin my trip'. I envisioned some disciplined, motivated Nick living the life of his dreams overseas, and that Nick always did what needed to be done.
When I was actually on my trip, though, reality set in. I was not that person. Things became inconvenient, and my statement immediately changed to 'I will start exercising at 7:00am in the morning when I get back from my trip and my life gets a little more stable'.
Likewise, when I started working for myself, I had statements of the form 'I will start writing every morning after I move out'. I was still living with my parents at the time, and (of course) there were distractions here or there, so I thought that it was too difficult to start now and I would wait until it got more convenient. Future me, who was independent, efficient, and unburdened by the distractions of home life, would surely feel motivated enough to write.
Wrong. The second I moved out, my y predictably moved goalposts when I realized how difficult and burdensome it was to hold myself to that standard. It later became 'I will start writing every morning after I sort out my finances' and eventually that too changed.
This type of goal-post shifting is endless and constant, and there seems to be something about it that is particularly gratifying to the human psyche. I suspect it has something to do with simultaneously committing to something difficult - which feels psychologically pleasant - while also promising yourself that you do not need to do that same thing just yet, which feels psychologically pleasant as well.
This is made more powerful through diffusion of responsibility. By saying that you will only start on x after y has occurred, you place the onus on y and not yourself to make it happen. This is relieving. To most of us, it's an attractive mode of mental 'problem solving' because it allows you to commit yourself to overcoming a problem without acknowledging that it is your responsibility to do so.
For years, I've witnessed the Postponed Start problem in my friends, family, and myself. It's not an isolated phenomenon. Because of how widespread it is, I've spent the last several months trying to find a solution to this crippling, demotivating form of self-defeat, and I've stumbled upon a consistent system that works for me.
First: if you're not willing to do it when it's hard, you won't be willing to do it when it's easy. If you aren't willing to do it now, because you're waiting for it to become more convenient with time (or a change of scenery), odds are you will never get it done. You must first acknowledge this fact.
Second: understand that, at the beginning, the quality of your work simply doesn't matter. For example, if your goal is to exercise each morning at 7:00am, understand that the quality of those workouts mean nothing if you can't even make it to the workout in the first place. Thus, it's better to completely rid yourself of the idea of quality, and instead focus on simply showing up. You can sort out quality a few weeks down the line once you've instilled your "x" as a proper habit.
Third: whenever you catch yourself building a Postponed Start excuse in your head like "I'll start doing x when y happens", replace the y with the real reason: "when I choose to do so". The responsibility is now completely on yourself, and this is both freeing and challenging.
At this point, you have no option but to start doing the thing. Immediately. Yes, it'll probably be inconvenient - you may be coming up with these ideas on the way to work, or perhaps in the middle of a shower. As soon as you're able, though, you must start accomplishing your task, because if you can do it when it's inconvenient and chafing with your schedule, it will become significantly easier to do it when it's convenient and something that you've specifically made time for.
The first time is always the hardest, but with the first link the chain is forged. The rest of your habits will follow automatically, so long as you build the conscious understanding that it is your responsibility to accomplish the task and no event or circumstance can dictate it but you.
Remember: a large part of your brain is nothing more than a hastily put-together defence against hard work. For evolutionary reasons, your mind is always searching for ways to avoid problems. Coincidentally, it also often defines a problem as anything requiring the excess usage of calories, which nearly all economically beneficial tasks in the twenty first century are. If you can understand that, and build robust systems to catch your irrationalities before they become life-crippling problems, you will succeed every time.