Something clicked while I was reading Poor Charlie’s Almanack, a compilation of Charlie Munger’s speeches over the years. The book highlighted Munger’s approach to investing and, more importantly, his approach to life. While there’s a lot of useful worldly wisdom in there, my greatest takeaway was to have a checklist.

Think of it like an airplane preparing for takeoff. Nothing happens until the preflight check is complete.

It’s simple, yet powerful.

Now, you might hear a lot of people raving about Charlie’s mental models, going through them individually, but not really explaining how to use them as a whole.

Before going into details, what’s a mental model anyway?

Simply put, a mental model is an idea or concept that’s compressed so you can recall and apply it quickly. It’s like design patterns in programming.

But not all mental models are made equal, if we were to rate them, there are only a few that are considered S tier – like “first principle thinking” and “second-order effects“. Such mental models could be applied to any decision-making process. And as I used more of them in my life, I quickly realized that the best general mental models are the ones that generate options.

Another common mental model is confirmation bias, where someone retrofits their beliefs to circumstances. As the saying goes, “If all you have is a hammer, every problem looks like a nail.”

I’ll admit, I’ve made rookie mistakes with mental models. I remember having a conversation with a friend who was in a particularly sticky situation. After she shared her story, I asked if I could take a minute to look through my personal notes. I was trying to find a mental model to fit her circumstances.

I messed up for two reasons. First, I was only looking for only one mental model. Second, there might have been other models that could have helped her better. It’s like what Simon Sinek said: instead of looking at strengths and weaknesses, he looks for characteristics and attributes. These become strengths or weaknesses depending on the circumstances.

As more information about mental models becomes readily available, the ultimate goal is to have a set of checklists so that you can use them systematically. There aren’t many S tier mental models and if we want our decision making model to be all-encompassing, we need to include other mental models.

We should see mental models as if they’re like wind: “it extinguishes a candle and energizes fire.” Different models apply differently, and the wonder of Charlie Munger was that he could apply the same concept to various scenarios. In his book, he illustrated how different mental models (including biases) could interact with each other and how the effects of this mixture could help turn millions into billions over time.

When we watch interviews of the G.O.A.T, they are able to articulate their decision making process as if it’s second nature. We might think it’s easy, but it’s not. They’ve gone through a great amount of trial and error before their checklists were shaped to make them the greats they are.

There is also another less obvious benefit of having a checklist and that is it gives you the opportunity to review and refine your decision making process. Could you think of the last time you made a major decision and reviewed how it turned out? Like many aspects of any system, it gets better with a large number of iterations.

So, before you take off towards your next big decision, it’s worthwhile to consider doing a preflight check. Who knows, this simple addition could bring you to greater heights.