How the planning fallacy stops your progress

written by Philip Stefanov  |  DECEMBER 14, 2021

Like most people, you probably have a high opinion of your ability to plan and estimate how long tasks would take you to complete. I know I do.

The problem is–and this might come as a surprise–we are terrible at estimating how long different objectives take. We often err on the side of optimism, leaving little room for error, delays, and unexpected issues. 

The Planning Fallacy In Action

The planning fallacy is a phenomenon that describes our tendency to underestimate how long something would take. Psychologists first coined the term in the late 1970s.

Perhaps the most famous example of the planning fallacy is the construction of the Sydney Opera House. What began as a straightforward project took ten extra years and $100 million more to complete.

The planning fallacy occurs because we tend to:

  • Overlook crucial details
  • Fail to realize that unexpected problems will arise
  • Forget past experiences

Instead, we prefer to err on the side of optimism, hoping to accomplish goals quickly and with ease.

For example, if you need to fix up your kitchen, you might conclude that the project will cost you $1,500 and take a couple of weeks. But, as you start work, you will inevitably run into issues and details you hadn’t considered. The many small factors can considerably lengthen the duration and inflate the cost.

The Planning Fallacy And Our Fitness Aspirations

Countless people set themselves up for failure precisely because of the planning fallacy. Like many, I fell for the fallacy when I first started my fitness journey. I weighed over 240 pounds back then, so I decided to diet. I remember thinking that I would probably have to diet down to 200 pounds to be lean and that I would do that in a couple of months.

First, it took me over four months to shed the 35-40 pounds. Second, I looked nowhere near done with my weight loss at 200 pounds. I was still overweight and didn’t like how my body looked, so I kept on dieting.

Three or four months later, I had lost another 30 pounds and was finally getting to a place where I liked the results. But I grossly underestimated:

  1. How much weight I would need to lose to be satisfied
  2. How long it would take me

What began as a two-month diet morphed into an 8-month process that presented me with countless setbacks and frustrations.

What Does It All Mean?

Well, it means that we are terrible at estimating how much time or effort things will take us. The planning fallacy applies to minor and major things in life, from commuting to a new workplace to losing weight.

Whatever goals you want to achieve, I recommend always leaving extra time and accepting that it will never be smooth sailing from start to finish. Unexpected issues will arise, you will slip up, and you will have to adjust the course to keep making progress. For example, if you think a diet will take you two months, double that time and thank me later.

Thank you for reading! Until next week,


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