The gain that had to be forgone in order to achieve something else makes opportunity cost the best alternative to forego. For instance, I planned to sleep till dawn today, but I remembered I had a test, so I got up earlier to study. The delight I forwent in order to study for my test is the opportunity cost, which is the sleep.
Daily situations involving opportunity cost occur in our lives.
This economic theory basically comes into play when we have to give up something in order to obtain something we think will be more beneficial.
Another instance of opportunity cost is forgoing a movie to study for a test.