Both optimism and pessimism have their downsides: Optimism can lead to a blind negligence of facts, while pessimism keeps us from taking chances and starting new things. To make the best of both sides, we have to swing back and forth between them.
When starting something, pessimism would keep you from it or make you sabotage the project because you want to be right with your pessimism. So, you have to be overly optimistic: Take a risk, do what’s unconventional. Take the first step and get started.
Now that the initial barrier is passed, you have to switch to pessimism: ruthlessly attack your idea from all sides and strive to make it flawless. The purple glasses of optimism would only lead you to ignore some risks.
At some point, however, you must ship – staying pessimistic would mean perfectionism and never finishing anything. Thus, you switch to optimism again to eventually get your project done.
What if you’re in doubt, what if your idea doesn’t work out as imagined? The same rule applies: First, be optimistic. Plow through. Every successful project faces adversity at first. If it still doesn’t work out, honestly consider whether another option may be worthwhile – of course your project may work out at some point, but it would take a lot more work than other things. In that assessment, be pessimistic. See all the downsides. Look at the data. You will decide to quit 9 out of 10 projects. And that’s fine – that’s how innovation works. The one project you don’t quit is the one that pays the nine quit ones.
Make your attitude a pendulum: Be optimistic first, and pessimistic when appropriate.