Question pertaining to The One Thing

[Andres Felipe Aristizabal]

Hi BP Community!

I've been learning and attending real estate investing meetings for the past couple of months now. I recently started reading The One Thing by Gary Keller, and came across the part where he asks the guitar teacher if he had to learn one thing from guitar (with the limited time that he had to learn) what should he learn. In other words I guess, what would be what he considered to be the most important thing to learn. Now I'm not saying that I'm limited in time, but I am curious to hear from others who already find themselves investing what they would consider to be that one thing. What is the one thing, if someone had to learn something about real estate investing, that you believe would constitute as being the most significant/important to know/understand? And why?

Thanks!