Why You Should Keep a Not-To-Do List (and What Goes On It)

Warren Buffett has a well-known exercise he recommends to people asking about focus. Write down 25 things you want to do in your life. Circle the top five. The remaining 20, he says, go on your "avoid at all costs" list — not because they're bad, but because they'll steal time from the five that actually matter. The twenty are the enemy of the five, not the supplement.

This is the not-to-do list, which Buffett popularised but didn't invent. Versions of it appear in Peter Drucker's writing from the 1960s. The modern treatments include Jim Collins's "stop doing" lists and Greg McKeown's essentialism. The concept keeps resurfacing because most ambitious people fail at focus not for lack of a to-do list, but for lack of its opposite — a specific, maintained list of the things they are consciously not going to do.

Why a Not-To-Do List Works When a To-Do List Doesn't

A to-do list is a container. As your capacity and ambition grow, it fills up. The more you can handle, the more you take on, until the list's content exceeds the time available to execute it. This is not a failure of planning; it's the structural behaviour of a container with no limit.

A not-to-do list is the counterweight. It names, specifically, the categories of work and activity that you're not taking on — not because they're bad, but because they're not the five. Every item on the not-to-do list is a piece of capacity preserved for the to-do list items that matter.

The asymmetry: adding to a to-do list is frictionless; adding to a not-to-do list requires deliberate choice and causes discomfort. This is why the not-to-do list is uncommon. The discipline is harder than the discipline of building a to-do list, which is why it produces more value.

What Actually Goes On It

Three categories of items are typical on a serious not-to-do list.

Category A: Specific activities you're rejecting

Things you could do, that other people might expect you to do, that you're consciously not doing. For a senior manager, this might include:

• Attending optional industry conferences unless genuinely relevant
• Speaking at events that don't align with specific career objectives
• Taking on advisory or board positions outside your primary focus areas
• Writing in formats other than the one you've chosen to concentrate on
• Meeting with anyone who asks, for coffee or a call

Each of these is a category of activity, not a specific task. The value of listing them: when the specific invitation arrives, your decision is pre-made. You don't need to think about it; it falls in the "no" category by default. This saves cognitive cycles and, more importantly, protects you from the in-the-moment politeness that would otherwise produce a yes.

Category B: Skills you're not going to develop

A more uncomfortable category. You can't be excellent at everything. The attempt to be well-rounded across too many skills produces mediocrity in all of them. The skills you're not going to develop get listed explicitly so that you stop feeling guilty about them.

Examples, at the senior level:

• "I'm not going to become a competent public speaker." Valid if your role doesn't require it.
• "I'm not going to learn to code." Valid for most general-management roles.
• "I'm not going to build a large social media following." Valid unless your career specifically depends on one.
• "I'm not going to become a detailed project manager." Valid if you can hire or work with people who are.

The psychological effect: energy previously spent on guilt or half-efforts in these areas is redirected. You stop feeling bad about not being a public speaker and start investing the time in the skills you've decided to develop instead.

Category C: Behaviours you're trying to eliminate

Specific patterns you've identified as counterproductive, listed as explicit commitments to stop. These are harder than categories A and B because they're about self-management rather than external boundaries.

Examples:

• "I'm not going to check email before 09:30."
• "I'm not going to make decisions in the 20 minutes after receiving a critical email."
• "I'm not going to continue conversations on Slack past 19:00."
• "I'm not going to volunteer opinions in meetings where my view isn't being solicited."
• "I'm not going to take on projects where I can't name the specific business outcome I'm producing."

The self-management items are where the personal growth happens. They represent behavioural patterns you've observed in yourself that aren't serving you. Naming them on the list makes them visible; making them visible is the first step to changing them.

The Review Cadence

The not-to-do list, like any other commitment document, only works if reviewed. The cadence that works for most people: quarterly.

Every three months, 30 minutes, open the list. For each item: am I still avoiding this? If yes, great. If I've been slipping, why, and what adjustment will bring me back to the commitment? Is this item still the right thing to avoid, or has the situation changed such that it should come off the list?

Items come off the list for three reasons: the underlying priority has changed; the avoidance has become automatic and no longer needs a conscious commitment; or you've decided, deliberately, that the thing is actually worth doing after all. All three are legitimate.

Items get added quarterly too. As your work and priorities evolve, new activities or behaviours emerge as worth avoiding. The list lives.

The Uncomfortable Part

A specific failure mode: adding items to the not-to-do list without actually committing to them. The list becomes aspirational — a catalogue of things you wish you were avoiding but continue to do. This is worse than having no list, because it creates a lie you tell yourself.

The discipline: don't list something unless you're actually going to avoid it. If you're not committed, it doesn't belong on the list. Some things belong on a "considering avoiding" list, which is a different document — a working-through exercise rather than a commitment.

The list's credibility to yourself depends on follow-through. An honest not-to-do list of seven items you actually avoid is more valuable than an aspirational list of twenty items you're half-following. Smaller and real beats bigger and notional.

The Meta-Question

The deeper value of maintaining a not-to-do list is that it forces you to confront, periodically, what you're actually optimising for. You can't meaningfully avoid things without knowing what you're avoiding them in favour of. The exercise surfaces the question every quarter: what are my real priorities? Are the things I'm avoiding actually in conflict with them, or am I using avoidance as an excuse?

Most senior professionals think they know what they're optimising for — career progression, family, specific projects. When they sit down to write the not-to-do list, they often discover that their actual behaviour suggests a different set of priorities. The list is diagnostic. What you're willing to avoid reveals what you actually prioritise, as distinct from what you'd claim to prioritise.

This is uncomfortable and useful. Over a career, the cumulative effect of the quarterly confrontation is clarity — a closer match between stated priorities and actual time allocation than most peers ever achieve. The gap between what people say they value and what their calendars show is, for many professionals, the entire difference between a coherent career and a drifting one. The not-to-do list closes the gap slowly.

The Buffett Frame, Revisited

Buffett's original advice — circle five, avoid the other twenty — is more radical than most people accept. It suggests that the activities outside your top five are actively damaging to your top five. Not neutral. Damaging.

This is uncomfortable because we like to believe we can do many things well. Buffett's argument, borne out by his own career of famously narrow focus, is that real excellence requires the elimination of diluting activities, not just the addition of focused ones. You can't build a top-five career while also doing a dozen other things at 60% intensity. The twenty secondary items will steal time, attention, and emotional energy from the five, and the five will suffer.

The implication: the not-to-do list is not a nice-to-have for ambitious people. It's structurally necessary. The person who claims to have "too many priorities to pick just five" is usually a person whose top priorities aren't actually going to be achieved. The ruthlessness of the Buffett exercise is not an aesthetic choice. It's what the math of focus requires.