From John Dewey’s How We Think:

Direct immediate discharge or expression of an impulsive tendency is fatal to thinking. Only when the impulse is to some extent checked and thrown back upon itself does reflection ensue. It is, indeed, a stupid error to suppose that arbitrary tasks must be imposed from without in order to furnish the factor of perplexity and difficulty which is the necessary cue to thought. Every vital activity of any depth and range inevitably meets obstacles in the course of its effort to realize itself—a fact that renders the search for artificial or external problems quite superfluous.

A repeated point I’m picking up from Dewey is that “vital activities” (which I think map fairly closely to what we call “authentic tasks” now?) are the only way to learn. You’re either learning by participating with your community in an activity vital to life, or you should just stop.