Patience.

Yûnus ibn Yazîd said I asked Rabî‘ah ibn Abu ‘Abdur-Rahmân:

“What is the ultimate of patience?” 

and he said: 

“To be outwardly the same at the time of affliction as one was the day before it struck.” 

Heyy but this does not mean that a person does not or should not feel pain or anguish; patience in this instance means that one refrains from panicking and complaining. =)

-taken from Drop of Wisdom-