66 Day Challenge: Rules, Free Printable PDF and Rewards for Every Stage

The 66 day challenge is simple: pick one habit and do it every day for 66 days. Not 21, not 30. Sixty-six is roughly how long it takes for a daily habit to start running on its own, so the challenge is built to carry you past the point where most people quit.

Below: where the number comes from, the rules, habit ideas, rewards for each stage, and a free printable tracker.

Where 66 days comes from

In 2010, Phillippa Lally and colleagues at University College London asked 96 people to pick one eating, drinking or exercise behavior and do it once a day in the same situation, like “drink a glass of water after breakfast”. They tracked how automatic it felt. The median time to reach the plateau was 66 days, and people ranged from 18 to 254 days. Simple habits like drinking water came faster than exercise. The study is in the European Journal of Social Psychology; we cover it in more detail in how long it takes to form a habit.

Two popular books made the number famous:

The ONE Thing (Gary Keller and Jay Papasan) uses the research to argue that you don’t need more discipline than it takes to build one habit at a time, for about 66 days. That’s where the “one thing 66 day challenge” comes from, and why real-estate agents know it from Keller Williams.
The 5AM Club (Robin Sharma) describes installing a habit over 66 days in three 22-day stages: destruction, installation and integration. Our tracker follows the same three stretches: the hard part, the messy middle, and the part where it starts to run on its own.

The rules

One habit. The whole point is focus. Pick the one that would make the most other things easier.
Small enough for your worst day. “Write 200 words”, not “write a chapter”. You can always do more.
Same trigger every day. After coffee, after brushing your teeth, when you sit down at your desk. Lally’s participants did their habit in the same situation each day.
Never miss twice. In Lally’s study, missing a single day didn’t materially slow the habit down. Don’t restart the count; just don’t let one miss become two.

Habit ideas for 66 days

Health: a 20-minute walk, 10 push-ups, a glass of water before coffee, in bed by 11.
Mind: 10 minutes of reading, 5 minutes of meditation, three lines in a journal.
Work and study: one focused hour before email, 20 minutes on the language you’re learning, 200 words a day.
Home and money: a 10-minute tidy, no-spend weekdays, writing down every purchase.
Quitting: no phone in bed, no alcohol on weeknights, no snacks after dinner.

Need more? See 100 habit tracker ideas or how to stack a new habit onto one you already have.

Rewards for every stage

Sixty-six days is long enough that “the habit is its own reward” doesn’t hold up in week three. Plan rewards before day 1, small and soon at the start, with the biggest at the end. The printable has seven reward days:

Day	Why it’s there	Reward ideas
7	The first week is proof you can start	A favorite coffee, an episode guilt-free
14	Novelty is gone	A new book, a takeout night
22	End of the hard part	A movie night, a long bath, a class you’ve wanted to try
33	Halfway	Something for the habit: new running shoes, a nicer notebook
44	End of the messy middle	A day out, a concert ticket
55	The last stretch	A massage, a game you’ve been waiting for
66	Done	The big one: a weekend away, the thing you’ve been saving for

Two rules for rewards: don’t pick anything that undoes the habit (a cake for a sugar-free challenge), and claim each one on its day, not before. More ideas: 70 ways to reward yourself.

Free printable 66 day challenge tracker

A printable 66 day challenge tracker with 66 numbered boxes in three stages and reward days marked in gold

Download the 66 day challenge PDF (US Letter; prints on A4 with “fit to page”). It has 66 numbered boxes in the three 22-day stages, gold reward boxes on days 7, 14, 22, 33, 44, 55 and 66, a reward list to fill in before you start, and the four rules. Stick it on the fridge or the bathroom mirror: a chart you see every day is half the trick.

Track it in an app

If you’d rather not keep a pen by the fridge, Habit Rewards does the same thing on your phone. Add the habit with a start date and an end date 66 days later, and set a reminder at your trigger time. Each check-in pays coins by how hard the habit is (1, 4, 8 or 16), and you put your stage rewards on your reward list with a coin price, so the day-22 movie night is something you can see getting closer. If a day goes wrong, a Skip costs 10 coins and keeps your streak alive, which is the “never miss twice” rule with a price on it.

It’s free for three habits and three rewards on iPhone and Android. For a shorter warm-up, try the 30 day challenge first.

FAQ

What is the 66 day challenge? Doing one habit every day for 66 days, the median time it took people in a University College London study for a daily habit to become automatic. It was made popular by the books The ONE Thing and The 5AM Club.

What are the rules of the 66 day challenge? One habit, small enough for your worst day, done after the same trigger every day, for 66 days. If you miss a day, don’t restart: just never miss twice.

What if I miss a day? Keep going. In the study, missing one day didn’t materially affect how automatic the habit became. What hurts is stopping.

Is 66 days enough to form any habit? It’s a median, not a guarantee. People in the study took anywhere from 18 to 254 days, and exercise took longer than simple habits like drinking water. If the habit still feels like effort at day 66, keep the chart going.

Is there a 66 day challenge app? Any habit tracker with a streak works. Habit Rewards adds rewards: each day pays coins you spend on rewards you set for the milestones. The free printable above works too.

✅ Try Habit Rewards: the habit tracker that pays you

Every habit pays coins by how hard it is (1, 4, 8 or 16). Write your own reward list, put a coin price on each treat, and claim it once you've earned it.