How to Build a 90-Minute Focus Block When You Can't Concentrate

The task you meant to start in the morning still hasn’t been started by late afternoon. On most days when concentration feels impossible, the problem isn’t that your attention has degraded. It’s that every door an interruption could walk through was still open when you sat down.

In what to do when you keep reaching for your phone at work I covered three things together: notifications, where the phone sits, and picking one protected slot. This article takes that last item — one 90-minute block a day — and works only on what goes inside the 90 minutes. And not just phone interruptions: meetings, chat, and your own stray thoughts all get a door closed on them.

There’s nothing magic about 90 minutes

Being honest up front: no study backs the number 90. It’s a practical length.

• One slot in the morning or afternoon usually fits between meetings
• It’s long enough to take one task through research, drafting, and revision
• At once a day, you can lose it to a chaotic schedule and still get it back tomorrow

For a sense of scale: in a survey of 606 working adults in Japan (conducted November 2024), the 450 respondents who said they felt dependent on their phones reported an average of 264.7 minutes of daily use, and said they could go an average of 197.2 minutes without touching the phone. Those are self-reported averages rather than measurements, but 90 minutes sits comfortably below what most people estimate they can already manage. You’re not setting an unreasonable target.

Sort interruptions into three kinds, then close each door separately

Plenty of advice promises to improve your concentration, but if you don’t separate interruptions by where they come from, one of them always survives whatever single fix you apply. Protecting 90 minutes means handling each entrance on its own terms.

Kind of interruption	Examples	What to do before the block
Comes from the phone	Opening social, video, or news; reaching for it when a notification lands	Put the device in another room, and have the OS keep those apps closed for exactly that window
Comes from other people	Meetings, a chat ping, someone at your desk	Block the slot on your calendar so it reads as a commitment. Set your chat status to away with the time you’ll be back
Comes from you	Remembering another task, drifting into a side search	Write it on paper (see below)

Don’t underestimate the third one. You can put the phone in a drawer and close every chat window, and the moment you think “I should check on that other thing,” your focus breaks exactly the same way.

Decide the first five minutes in advance

A 90-minute block usually falls apart in the first five minutes. If you haven’t decided what to touch first, those five minutes go to hunting for a file or glancing at email, and half the window is gone before you notice.

So when you create the slot, write down the single action that starts it. Something as concrete as “open the estimate spreadsheet and fill in from row 3.” With that decided, there’s no thinking to do once you sit down.

Send stray thoughts off the screen

The fix for self-generated interruptions is a sheet of paper and a pen next to your screen. When something surfaces, write it down and look at the list after the block ends.

• “I never filed that expense report” → write it
• “I want to read that article” → write it
• “Someone’s probably waiting on my reply” → write it

The temptation is to track this in an app, but the screen you open a notes app on is also the doorway to every other app, so keep it on paper for the 90 minutes. There is evidence that adding a pause before you open something works: in a six-week field experiment with 280 participants (PNAS 2023, the study behind one sec), participants closed the app outright in an average of 36% of the moments where the intervention fired, and by week six they were attempting to open the target apps 37% less often than in week one. What does the work isn’t force — it’s the extra step. For where the device itself should live, see giving your phone a parking spot.

If it doesn’t stick, drop to 45 minutes

If 90 minutes collapses after two days, the length is simply wrong for your schedule. Drop to 45 and put a 10-minute break at the end (keeping that break off the phone is covered in how to take a break without opening your phone). A short block you clear every day is easier to come back to than a long one you manage once a week.

If it starts feeling easy, resist adding a second block. Swap heavier work into the one slot you already have instead. More slots just means losing all of them on the first disrupted day.

Do this today (10 minutes)

• Put one 90-minute block on tomorrow’s calendar, in a window meetings rarely land in
• Pick the single task for it, and write the first five-minute action
• Set one OS-level limit so social and video stay closed during that window
• Put paper and a pen on your desk
• Add your return time to your chat away status

Once tomorrow’s block holds, repeat it at the same hour for a week. Moving the slot around every day means renegotiating your schedule every day, which is why it stops happening.

Sources

• Job Soken (Persol Career), “2024 Survey on Smartphone Dependence” (606 working adults in Japan, surveyed 6–11 November 2024, online survey. The 264.7-minute and 197.2-minute averages are for the 450 respondents who reported feeling dependent): https://prtimes.jp/main/html/rd/p/000000227.000013597.html
• Grüning, D. J., Riedel, F., & Lorenz-Spreen, P. (2023). Directing smartphone use through the self-nudge app one sec. PNAS, 120(8) (six-week field experiment, 280 participants): https://www.pnas.org/doi/10.1073/pnas.2213114120

This article summarises publicly published surveys and is not medical diagnosis or advice.