Challenge Thyself
Typically when people use the phrase, "go out of your comfort zone," they're referring to engaging in activities that purposefully make you uncomfortable. And on the surface what they mean is skydiving or triathlons, extending the boundaries of their physical self and abilities by challenging themselves to learn something new, see new things, push themselves one more mile. But of course, underneath that is building one's mental resilience: self-compassion, determination, and courage. This is one way we can grow, as long as we're open-minded enough to appreciate the experience.
Take a moment now and think of a time someone disagreed with you on something complicated like a political subject or a solution to a problem at work. This is another way to "go out of your comfort zone." The challenge thrown at you now however is a very different one. Empathizing with another's perspective and opinion and interpreting their argument on its own while resisting your emotions distortions. We human beings are delightfully, yet unfortunately, predisposed to the biases of our emotions. At times our biases yield an upwards cycle. Like when we're happy to see someone and our happiness infects the recipient of our smile so that our next interaction is likely to be equally or more joyous. On the other hand, these same biases can cause us to undervalue another's viewpoint simply because we're mad they never returned our stapler on time.
If you can overcome this natural tendency, you stand to gain some equally valuable traits: empathy and wisdom. The ability to do this though, to suppress reaction and grow in this capacity requires its own exercise. The first skill we must exercise is mindfulness. If we learn to let our emotions flow by us, acknowledging them without engaging them, we give ourselves the opportunity to see the world as another does; to let their words stand for themselves; to judge the flimsiness of their logic without anger, disgust, or any of our more dismissive emotions. The second thing we must develop is our devil's advocate. One obvious way to do this is simply to seek out opinions and resources we disagree with. It's a rare invidiual that does this, but stretching your boundaries in this way will make you surprisingly worldly. There is one more thing you can do though.
We can be vigilant of our own thoughts. We all hold opinions with unknown origin and facts we can't remember the source of. If we can challenge them ourselves, in this way we can grow even without any resources or adventures (though having them is obviously best!). This is what it means to Challenge Thyself. If we're diligent, we transform ourselves so that we're comfortable with uncomfortable, foreign thoughts. And if we can do that, then we can empathize with someone else if for no other reason then we've learned to emphasize with ourself. And once we've done that, we'll have the freedom to grow further.