I've noticed that most good teachers are their own worst critics. Sure, they say, use that evaluation rubric on me, and please, give me some critical feedback, but at the end of the day, you're not going to critique me more than I critique myself.
This disposition is important; it's one that distinguishes the Professional from the Technician. But there's an important addition here that I think separates the good teachers from the best ones: joy.
When we root our identity in something larger than how the work goes today, how the test scores come back, how the essays look, or what the parents say — in other words, when our locus of identity is internal versus external — it becomes possible to be simultaneously critical and joyful. Joyful self-critique isn't a requirement if your objective is to do the work well for a couple of years, but I do think it's a requirement if you want to build a meaningful, lifelong career. The teacher who becomes her own worst critic is able to withstand the tides of policy change and the rise and fall of accountability regimes, and the teacher who can do harsh self-critique with joy is able not just to withstand but, shockingly, to flourish despite the conditions.
This doesn't mean taking joy in poor student outcomes, in shoddy student work, in the latest, most urgent kid whose life is unraveling. Rather, it's taking joy in the work of getting better at preventing the bad things and promoting the good, all the while teaching at the edges of our capabilities.
The wise school leader will fight to make room for joyful self-critique and will communicate this as a cultural value. The wise teacher will make room for this kind of reflection, even if it means satisficing other, less purposeful tasks.