I’m currently doing an experimental pilot course  with Cal Newport  about applying the ideas of deliberate practice to a career setting. To get better feedback, we limited the course to fifteen people.
We also had the potential applicants jump through a number of hoops to eliminate the uncommitted. A $500 tuition fee, application form including a short essay response and even an honor agreement signed by each participant that they confirmed they were committed for the course. Finally, I went through each application by hand, eliminating people with any red flags that they weren’t completely dedicated.
I probably won’t get such a highly filtered group of candidates for any course I run again.
Given that stringency, what percentage of students do you think fulfilled the only commitment of the course for the first week: investing exactly five hours of time?
Only 47%. Less than half.
Now I’m not trying to criticize the students. To their credit, we did get full responses from every member which is the reason I know 53% of them had difficulty sticking to their precommitted time in the first week.
In fact, I am also shadowing the course curriculum to understand it better. And in my first week I nearly missed the final hour I had scheduled!
My point isn’t to blame the candidates, as I think they’re doing remarkably well. Instead it’s to point out how much more fragile our self-discipline is in reality than in our mind. During the application process, asking the students to commit to five hours a week was easy. However once we started, many found it much more difficult, even in the first week.
Why Plans are So Unrealistic?
What happened? Why did half of the students, and nearly myself as well, fail to put in the minimal commitment of five hours per week to an expensive course they had jumped through hoops to get into?
My answer: because plans are simple and reality is complex. Your plans for the day or week can be crisp chunks of scheduled time, forming neat colored blocks on your calendar. Life is a messy assault of interruptions.
The result is that your ability to commit to things in theory, is much stronger than in practice.
The 20% Rule
Imagine you were a person with a fifth of your normal discipline, willpower and free time. How would you make a plan to accomplish the goal in front of you? Now make that your actual plan because the 20% you is closer to reality than your planning fiction.
That means if you think you could commit ten hours a week to a new goal, ask yourself how you’d set it up if you could only do two hours. You may end up doing more than two, but it’s a more realistic starting point than ten.
Most of the time this rule isn’t quantitative. It just serves as an exercise for reimagining plans with significantly less time or energy.
When I got back to Canada, I decided to restart my Anki  studying for Chinese. The first few days, I learned 100 new flashcards. In my enthusiasm, I felt like I could probably keep going at this rate and quickly finish the cards I didn’t have time to learn in China.
Then I remembered the rule, cut my new intake down to just 25 new cards each day. Sure enough, a week later, I was just barely keeping up.
What if Your Plan Isn’t Possible at 20%?
I realize the absurdity of me writing about plans with 20% effort. By that logic, completing the MIT Challenge  on-time would have meant I could have foreseen doing it reasonably in 2.5 months.
So, to the rule, I add an exception: you can safely predict your future capacity to execute a plan by your past capacity. If you plan to go to the gym every day, and previously you kept the habit of a daily exercise, it’s probably not an unreasonable belief that you can do it again.
Before the MIT Challenge, I had done a few courses outside of the curriculum and a pilot course under the exact conditions I wanted to replicate. Extrapolating one class to the remaining 32 isn’t guaranteed, but it’s a lot safer than trying to just imagine the time commitment without experience.
The 20% rule is, therefore, most useful when you’re tackling an unfamiliar kind of goal. The participants in our current course had never set aside exactly five hours for this kind of project. As a result, many had some initial hiccups as they encountered problems fitting it to their busy schedules.
Start Slow and Grow
If you need to tackle a challenging, yet unfamiliar goal, I recommend starting at 20% and moving upward. Figure out what you feel you could reasonably accomplish, cut it down severely and then slowly increase it as you get used to the habit.
- Writing. Think you can do 1000 words a day? Make it 200 the first week, 250 the next, etc.
- Exercise. Think you can do an hour a day at the gym? Start with 15 minutes.
- Reading. Want to read a book a week? Try reading 5 pages a day.
- Language learning. Start with a twenty minute lesson, once a week.
Hat tip to the ever-insightful James Clear  for the inspiration of this post.