Glossary

Opportunity Cost

Opportunity cost describes the value of the best alternative you forgo when you choose one option. Not just money, but also time, energy and attention.
Because these resources are scarce, every "yes" is an implicit "no" to something else.

Estimate opportunity cost by asking, "If I spend this hour on X, what high-impact Y am I not doing?". Consider impact, learning value, reversibility and deadlines. Noticing opportunity costs counters sunk-cost and status-quo biases.