“I think I just stopped growing here.”

It’s the resignation that blindsides you, because nothing was wrong. Your steadiest performer. No conflict, no complaint, handing in notice almost apologetically.

Mihály Csíkszentmihályi mapped the conditions for flow, that state of full absorption in good work. It lives in a narrow band where the challenge in front of you roughly matches your skill. Push challenge far above someone’s skill and they tip into anxiety. Let their skill keep climbing while the challenge stays flat, and they drift the other way, into boredom. Most leaders watch closely for the first failure. Almost no one watches for the second.

Boredom in a strong performer is nearly invisible. They still deliver, and they rarely name it, because “I’m under-stimulated” sounds ungrateful beside colleagues who are drowning. So the one signal you could act on never reaches you. And the pattern feeds itself. Because they’re reliable, you keep routing them the work you know they’ll land, and their competence earns them more of what they’ve already outgrown. The steadiness that should have been a warning just reads as dependability.

The departures that catch leaders off guard, across very different organizations, are seldom the people who were visibly struggling. They’re the ones who made hard things look easy for so long that no one thought to stretch them.

So in your next one-on-one with someone who never gives you trouble, swap “how’s it going?” for a sharper question: “Where do you feel stretched right now, and where are you coasting?” Then act on the coasting. Hand your most capable person the unfamiliar, slightly-too-hard thing, not the reward of more safe work.

Picture your most dependable person. When did you last give them something you weren’t sure they could do?