Unflapplable

Unflappable - usually calm in difficult situations.

Example - "I prided myself on being unflappable even in the most chaotic circumstances"

Image - http://www.azquotes.com/picture-quotes/quote-my-heroes-have-always-been-the-hardworking-and-unflappable-those-who-light-a-candle-matthew-gray-gubler-63-89-01.jpg