Become useful enough that problems start looking familiar.

Familiarity is what makes problems manageable, and it comes from having handled enough of them that new ones resemble old ones. Someone useful across many situations is not calmer by temperament, they simply keep encountering variations of things they have already survived.

Take on a wider range of problems than your role strictly requires. The breadth is what makes future difficulties recognizable, and recognition is most of what composure is made from.