What is a good antonym of "comfort zone", or an expression replacing "outside my comfort zone"? I'm writing an essay and don't want to repeat myself too much.
You could say "pushes your personal boundaries" or "pushes the envelope." It doesn't necessarily mean that it is a bad thing, but it does imply that you are doing something that is difficult for you.
How about "It makes me uncomfortable"? That's straightforward and seems to be what you mean.
Leon Festinger's concept of cognitive dissonance might help you.
When you are in your comfort zone, you are at ease and free of anxiety. When you experience cognitive dissonance, you are ill-at-ease and anxious. In other words, you've lost your equilibrium or homeostasis; you're out of your comfort zone. The following illustration is probably better than a thousand-word definition.
You arrive in Las Vegas with $500 in mad money in your pocket. Before stepping into a casino, you swear to yourself that once the five-hundred is gone (of course, that will never happen, right?), you will quit and walk out of the casino. A couple hours later, you've lost it all. You are now out of your comfort zone. What do you do? Walk out? Perhaps, but perhaps not. You have just entered the realm of cognitive dissonance. Why? Because you are in the classic "on the one hand, but on the other hand" situation!
Since most folks find it difficult to hold two conflicting ideas in their minds at the same time without feeling this dissonance, they kind of weigh the alternatives, make a decision, and then convince themselves through the process of rationalization that they've make a good decision, one that restores their equilibrium and gets them back into their comfort zone.
The gambler in my illustration, who now is really stinging from having lost his mad money, probably has a little talk with himself, which might go as follows:
Before having this little talk with himself, our gambler experienced a swirl of emotions in his head: regret, sadness, anger, frustration and shame, to mention just a few. This swirl of emotions created dissonance, and to quell it, he made a decision. It may not have been the right decision, but it at least frees him up to do what he's decided to do--maybe.
The scenario could unfold in any number of ways once he re-enters the casino. After losing 50 of his 100 bucks, he might have an epiphany and immediately storm out of the casino. The inner conversation he has prior to his departure is likely short and sweet: "That's it, I'll never gamble again!"
If, however, he stays until he's lost the hundred bucks, the situation might unfold as follows: "Oh, brother, I've lost another hundred. I know I said I'd leave if I lost the hundred, but I just KNOW I can pull ahead. After all, I did win $200 a half hour ago, even though I lost it with another stupid bet. I'll get just another hundred from the cash machine, and this time I'll really stick to my guns. If I lose that, I'm outa' here." And so it goes.
Since many--if not most--folks can't tolerate the feeling that a decision they're making is at the same time both crazy AND sane, they convince themselves it's one or the other. Sometimes the sane thing to do is cut their losses. Even though it hurts in the short run, it saves them grief in the long run. Sometimes, however, they refuse to cut their losses and forge ahead. Why? Because it's crazy NOT to!
Are we humans the rational critter or the rationalizing critter? You be the judge.
I hope this long-winded answer is of some help.