Most of us underestimate the time it will take to complete a future task. This planning fallacy is at work when that little weekend kitchen repair job turns into a month-long saga and it gets worse with more complex tasks. In terms of your financial life few tasks are as complex, or challenging, as saving for retirement.

Many of us will set aside our 40s and 50s as time enough to save for retirement, while living the good life in our 20s and 30s, when the sober truth is that there is no time to waste. We convince ourselves that we will save more of our income later in life to catch up on the years of not saving, but that invites a similar cognitive trap: excessive optimism about the future. It also fails to take into account that time allows our money to grow exponentially thanks to the power of compounding.

A practical thought experiment to illustrate just how little time we have to save is to think about the long term as a very short period of time.