The way our lives turn out is the result of two things: the influence of skill and the influence of luck. - Annie Duke

Forcing ourselves to express how sure we are of our beliefs brings to plain sight the probabilistic nature of those beliefs, that what we believe is almost never 100% or 0% accurate but, rather, somewhere in between.

The lesson here is that we shouldn't wait to be forced to find a Plan B. We should always be doing some exploration, especially because sometimes Plan B can turn out to be better than the thing you're already pursuing.

when we quit things, we usually follow the idiom out of sight, out of mind. We don't naturally track things that we're no longer in. This is likely what is causing the problem with the portfolio managers. When they enter into a position, they're tracking that every day, because it's part of the portfolio. But once they exit, they're not tracking it in the same way, because the position is now off their books. It's no longer part of their P&L statement, not as far as they can see in any obvious way.