The three questions a Stoic asks before the day starts: what Marcus Aurelius told himself each morning, and how to use it before work

Some time in the 170s, in a military camp on the Danube, the Roman emperor Marcus Aurelius wrote in his private notebook: "Say to yourself in the morning: today I shall meet the meddling, the ungrateful, the arrogant, the deceitful, the envious."

He was the most powerful man in the Western world, and he wrote those lines for nobody. The notebook was later published as the Meditations, but its Greek title means only "to himself". It is a man training himself, day after day.

The opening sounds bleak. Read on and it is clear he is not complaining. He is preparing. Someone who expects to meet a difficult person is less surprised when it happens, and less likely to react in a way they will regret. Three questions can be drawn from that habit of mind, and they take under two minutes each morning.

First: what today is actually in my hands?

Epictetus, the teacher Marcus Aurelius admired through his books, had been a slave before he became a philosopher. A story is told about him: his master twisted his leg to test him; he said calmly "you will break it", and when it broke, he said only "did I not tell you?". The story may well have grown in the telling, but it shows how he was remembered.

The handbook summarising his teaching opens with one sentence: some things are up to us, and some are not. You do not control what others think, where the market goes, or whether your body falls ill. You do control what you choose to do next, and how you look at what is happening.

The morning version: list three things you are worried about. For each, underline the part you can actually affect. "Will my boss approve the proposal" is not in your hands; "does the proposal answer the two questions my boss will certainly ask" is. The underlined part is usually much smaller than the worry, and that gap is what wears you out.

Second: if something goes wrong today, how will I respond?

The Romans called this premeditatio malorum, rehearsing misfortune in advance. The point is not to be afraid but to have a response ready when it happens, instead of inventing one while already angry.

We suffer more often in imagination than in reality. Seneca, in a letter to his friend Lucilius.

Two thousand years later, project managers rediscovered the idea. In 2007 the psychologist Gary Klein described in the Harvard Business Review a technique he called the pre-mortem. Before a project starts, the team imagines that a year has passed and it has failed badly, and each person writes down why. Klein found that framing made people voice risks they would normally keep to themselves.

At the scale of one day: before a tense meeting, prepare two sentences for if you are challenged. Only two. That takes most of the force out of the surprise.

Third: will this matter in ten years?

Marcus Aurelius often reminded himself of the scale of time: the famous men of earlier ages were already forgotten, and so he would be. It sounds gloomy, but he used it as a ruler. Most of what keeps us awake will not survive a year, let alone ten.

Seeing that does not make the problem disappear. It returns the problem to its true size. A clumsy remark in this morning's meeting probably will not matter. A decision about moving to another city to live with someone you love probably will. The question helps you separate the two, so your worry goes to the second kind.

Why therapy borrowed these questions

In the 1950s the psychologist Albert Ellis built a therapy that became one of the main branches of cognitive behavioural therapy. He said openly that he took his inspiration from a line of Epictetus: people are disturbed not by things but by the views they take of them. Today, separating "what happened" from "what I am telling myself about it" is one of the most basic exercises in cognitive therapy.

These three questions take under two minutes. Their effect does not come from the first time but from repeating them long enough to become reflex. Then you ask them in the middle of a bad day, waiting for the lift after a meeting that went wrong, not only on a quiet morning. Marcus Aurelius wrote the same ideas again and again in his notebook for years. Perhaps that is why.