Obvious: If you write things down, they’re more likely to get done.

Less obvious: If you write down a commitment to do something, and give that written commitment to people you respect and admire, then you’re even more likely to keep your promises. This is because you will have engaged one of the principles of persuasion.

In Influence: The Psychology of Persuasion, Robert Cialdini shares his comprehensive research into the psychology behind persuasion. Cialdini was, by his own admission, a terrible sucker for salesmen’s tricks and he sought to understand how marketers manipulated him into decisions he didn’t want to make.

One of the six universal principles of persuasion is commitment and consistency. Basically, you and everyone around you strive to remain consistent. Socially and culturally, it’s important that we are viewed as people who stick to their word, who make consistent choices and who can be understood on the basis of past actions. Inconsistent people are difficult, flaky, unreliable and undesirable. Clearly, in any society, consistency is a valuable trait, and the need to appear consistent is paramount.

It is this human need to appear consistent that marketers abuse. I won’t go into the depths of Cialdini’s fascinating research here (I recommend you read the book) but I would like to share one story from Influence.

A woman had struggled for years to quit smoking. In spite of reading numerous studies linking smoking to cancer, she hadn’t been able to quit. Eventually, after reading about yet another study, she realised that her pride was troubled. It was embarrassing for her to be smoking when it was so clearly a bad choice. She decided to use her pride and her need to be seen as consistent to help her quit.

She bought blank business cards and wrote, “I promise you that I will never smoke another cigarette”. She gave the cards to family, friends and, after some hesitation, the man she adored. Now, the woman hesitated before giving the card to her lover because she couldn’t risk him thinking less of her. By sharing the commitment with him, she was binding herself to it.

And it worked. She never smoked again.

So if you’re struggling to get something done, try writing it down and giving your promise to the people that matter most. Make your promise to the people that you could never disappoint.

Sometimes we can use the principles of persuasion against ourselves, in order to achieve positive goals.