There is an element of chance in everything we do. Call it chance, fortune, Lady Luck. Call it whatever you want. But it means that if you did great today, you’re doing worse tomorrow. Here’s why.

Imagine that you have an amazing writing day. Let’s say that you managed to type in 4000 beautiful words in a single afternoon, producing four times as much as you normally do. Everything is great. You’re totally on a roll.

Then you sit down the next day, and what happens?

You do worse.

You always do worse.

It hasn’t got anything to do with your skill, your execution, your planning, or your willpower. It has everything to do with chance and statistics.

It’s called regression to the mean.

Basically, it means that when you have an exceptional result, and there is chance involved, the probability that your next result is going to be even more exceptional is minuscule. Instead, your next result will likely be closer to your average.

Here’s some math.

Imagine you have a 10% chance of having a good writing day, 10% chance of having a bad writing day, and 80% chance of having an average writing day.

You might luck out, and have a good writing day today. But the chance of you having one tomorrow is still only 10%. So in 90% of the cases, you will have a worse day tomorrow, and in 10% of the cases, you will have an absolutely terrible day tomorrow.

And what’s the chance that you’re actually “on a roll?” If we define a roll as three or more good writing days, then, at 10% chance, the chance of you having another two is just 1%. That’s 1 in 100 that you will have three good days in a row.

There’s a famous story about the Israeli Air Force, where instructors had found that if they praised pilots who did well, those pilots would do worse. But if they yelled at and berated pilots who did poorly, those pilots would do better.

Enter Nobel Prize laureate psychologist and economist Professor David Kahneman. He took one look at their reasoning and gave all the instructors two coins, then put them in a line and asked them to each throw one of their coins over their shoulders, and land as close to the wall behind them as possible.

Some did well. Some did poorly. Most did somewhere in between.

And now Kahneman asks whether yelling or praise would have any kind of influence on how they threw their next coin. Of course not – but those who did well did worse with their second throw, and those who did poorly did better on average.

Regression to the mean.

This is actually great news.

Not because you’ll have a worse day if you do well. But if you have a really terrible day, an exceptionally bad day, one where you struggle and every word you manage to squeeze out of your bleeding mind just absolutely stinks, your next day will be better.

The risk of having two terrible days in a row is just as small as the chance of having two great days in a row. Instead, chances are that you will regress towards the mean. And since terrible is way below average, your next day should be better.

So what you should do is not to look at single days, even though they make for great stories and our brains tend to latch on to them. Instead keep track of your average over time because that is what will decide how well you will do in the long run, not your exceptional days, good or bad.

Now go write, and may the Math be with you!