As an opposing viewpoint, every major advance in my life has come from stepping outside of my comfort zone and tackling something in which I had no idea what I was doing.

-public speaking

-asking women out

-learning to dance

-socializing/making friends

-lifting weights

-starting a business

-doing sales work

-learning to program

edit: The vast majority of these made me very uncomfortable and awkard, not "a little".

"You're smart." It took me five years of coasting on that presumption before I realized that being "smart" isn't nearly enough. I'm still working (after a few more years) to develop the habits that would have come from hearing "you're a hard worker."

Not from any specific person, but the idea that you have to step outside your comfort zone and do X and Y even though it doesn't come naturally to you.

Every time I did that things got messed up and I ended up worse than I was before.

If you're outside your comfort zone, you will act in non-authentic ways, and when you're not being authentic, you can't be the best possible you.

Examples of stepping outside comfort zone:

* Wear a suite and act professional for a job interview

* Say hi to random strangers so you can make friends (even though you're introverted and doing this makes you look like a fool)

* Go to social events where you don't know anyone there.

EDIT: thanks for the down votes. Now let me explain why this is bad advice:

- Act not like yourself for a job interview:

This is bad because instead of showing them your strong points, you'll be busy trying to hide your weak points and seem like a "good, obedient" employee. Eventually you fail at both: your bad points will still show, while your good points won't get a chance.

- Begging friendship from random strangers:

Makes you look like a fool, insecure person that nobody wants to be friends with.

EDIT2: I'm not talking about little steps. Venturing into new areas is fun. Throwing yourself into the middle of an extremely uncomfortable situation is completely different.

One of the reasons I found "step outside your comfort zone" to be bad advice is that they never tell you how far to go and when you should stop. It seems consequential that you never know when you have gone too far, because you're outside the zone where you can use your intuition sensibly. If you were able to tell that you've gone too far, then by definition you're still inside your comfort zone.

If something only makes you a little bit uncomfortable, it will feel like it's still inside your comfort zone, and if you're trying to follow the "step outside your comfort zone" advice, you'll be tempted to go even further.