Schwartz's research suggests something important: we can stretch our personalities, but only up to a point. Our inborn temperaments influence us, regardless of the lives we lead. A sizeable part of who we are is ordained by our genes, by our brains, by our nervous systems. And yet the elasticity that Schwartz found in some of the high-reactive teens also suggests the converse: we have free will and can use it to shape our personalities.

Figure out what you are meant to contribute to the world and make sure you contribute it. If this requires public speaking or networking or other activities that make you uncomfortable, do them anyway. But accept that they're difficult, get the training you need to make them easier, and reward yourself when you're done.

Spend your free time the way you like, not the way you think you're supposed to. Stay home on New Year's Eve if that's what makes you happy. Skip the committee meeting. Cross the street to avoid making aimless chitchat with random acquaintances. Read. Cook. Run. Write a story. Make a deal with yourself that you'll attend a set number of social events in exchange for not feeling guilty when you beg off.

Introverts often work more slowly and deliberately. They like to focus on one task at a time and can have mighty powers of concentration . They're relatively immune to the lures of wealth and fame.

Do you really believe in what you said or wrote – in the thing that’s bringing criticism? And if I do believe it, I can withstand anything.

Shyness is inherently uncomfortable; introversion is not. The traits do overlap, though psychologists debate to what degree.

So stay true to your own nature. If you like to do things in a slow and steady way, don't let others make you feel as if you have to race. If you enjoy depth, don't force yourself to seek breadth. If you prefer single-tasking to multi-tasking, stick to your guns. Being relatively unmoved by rewards gives you the incalculable power to go your own way.