For eight years I've looked at other people's decisions for a living. First from the investor's side of the table, then from the founder's.

The ones who got it wrong were almost never the ones with less information. They were the ones who couldn't say what would change their mind, or who had been treating the same symptom for two years without ever asking what caused it.

Then it was my own company, and I learned that knowing all this doesn't protect you. Spotting a weak assumption in someone else's plan is easy. Spotting your own, on a Tuesday, when you're tired and the decision is due, is the part nobody trains.

So that is what this is. One short lesson a day: an idea, a real example, something to try.