There's stepping out of your comfort zone and then there's firing yourself like a human cannonball into the flames of high anxiety. Before my redundancy, I was doing the latter on a daily basis. And what worries me is that many of us can't see the difference between the two.
When we step out of our comfort zone, just like animals in nature, we're surviving a perceived threat. This stress response is designed to be fleeting, to help us when we're under pressure, not to be a default way of living — or working.