AI Guides › Playbooks
By Nigel Guy · 6 min read
Most people start a 90-day challenge with a big target and a vague feeling of commitment, then track it in their head. By week three the head has quietly dropped the days that went badly, and what remains is a mood, not a record. A tracker fails when it asks for too much (a spreadsheet of metrics) or too little (a tick with no evidence behind it).
The rule: one box per day, one tick, one line of evidence written the same day, and a pre-agreed plan for the day you miss.
A note on the source idea. This guide is built around a "$100K in 90 Days" style challenge that circulates online. We could not verify that challenge, its rules or any results people claim from it, so nothing here depends on it. The tracker works for any 90-day commitment: a product, a skill, a savings plan, a client pipeline. Nothing in it promises an income outcome.
It is a grid of 90 boxes, numbered 1 to 90, with a line of space beside or under each. Print it, or copy the layout below onto paper or into a notes app.
| Days | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
|---|---|---|---|---|---|---|---|---|---|---|
| 1-10 | [ ] | [ ] | [ ] | [ ] | [ ] | [ ] | [ ] | [ ] | [ ] | [ ] |
| 11-20 | [ ] | [ ] | [ ] | [ ] | [ ] | [ ] | [ ] | [ ] | [ ] | [ ] |
| 21-30 | [ ] | [ ] | [ ] | [ ] | [ ] | [ ] | [ ] | [ ] | [ ] | [ ] |
Repeat the block for days 31-60 and 61-90. Underneath, keep a ruled list: "Day 1 — ...", "Day 2 — ...". Cost at time of writing: £0 if you print at home or use a paper notebook.
Choose one action small enough that you can do it on your worst day. Write it as an if-then plan: "When I [CUE, e.g. sit down with my first coffee], I will [ACTION, e.g. work on the product page for 20 minutes]." Planning in this if-then form is called an implementation intention. A meta-analysis by Gollwitzer and Sheeran covering 94 studies found a medium-to-large average effect on goal attainment, but that is an average across many goals, not a guarantee for yours.
Two things, both on the same day.
If you cannot write the line, the box stays empty. The line is what stops the tick becoming theatre.
You will miss a day. Decide now what happens, so you are not negotiating with yourself while tired.
The research supports being relaxed about a single miss. In the UCL study led by Phillippa Lally, which followed 96 people for 12 weeks, missing one opportunity did not materially affect the habit-forming process. The same write-ups note that repeated misses did slow it. Treat that as a reason for the "never two in a row" line, not as permission to drift.
Read your own lines back. On each review day, answer three questions on one page: what did the lines show I actually produced, what kept getting in the way, and what will I change for the next 30 days? Change the action, not the target, unless the lines show the target was never realistic.
Imagine Priya, who wants to launch a small template shop in 90 days. Her Step 1 plan: "When I sit down after the school run, I will work on the shop for 25 minutes." Her day-4 line reads "Drafted descriptions for 3 templates." Day 12 she is ill, so the box gets a dash and "flu, slept all day". Day 13 she does five minutes and writes "Renamed files, nothing more." On day 30 she reads back 24 ticks, 6 dashes and a lot of drafting but no listings live. She changes the next 30 days' action to "publish one listing" and keeps the target. The review turned a vague worry into one concrete change. Priya is invented; the numbers are illustrative only.
The "one percent a day" idea is arithmetic, and it is worth checking rather than repeating. Improving by 1% a day compounds to about 2.4 times over 90 days (1.01 to the power of 90 is roughly 2.45). Getting 1% worse each day leaves you at about 40% of where you started. The same arithmetic over a full year gives roughly 38 times, which is why you will see that number quoted.
Two honest caveats. First, "1% better" is a metaphor: nobody can measure skill or output that precisely, so do not build a spreadsheet pretending to. Second, compounding only describes the shape of the idea, that small repeated actions accumulate, not that your results will follow it. Ninety boxes is a practical window, long enough to show a pattern, short enough to see the end. The Lally study found the time to reach automaticity ranged from 18 to 254 days, with an average of about 66 days, so 90 days will be too long for some habits and too short for others.