Cheerfulness

An individual’s actual (as a mood state) or habitual (as a trait or temperament) disposition for amusement and laughter including seeing the bright side of life and taking adversity less seriously.

Reference:
Bushman, B. J. (2002). Does venting anger feed or extinguish the flame? Catharsis, rumination, distraction, anger, and aggressive responding. Personality and Social Psychology Bulletin, 28(6), 724-731. doi: 10.1177/0146167202289002.

Bushman, B. J., Baumeister, R. F., & Phillips, C. M. (2001). Do people aggress to improve their mood? Catharsis beliefs, affect regulation opportunity, and aggressive responding. Journal of Personality and Social Psychology, 81(1), 17. doi: 10.1037/0022-3514.81.1.17