Gratitude

An emotion experienced when individuals perceive themselves to be recipients of an intentionally rendered benefit that is both valuable to the beneficiary and costly to the benefactor.

Reference:
McCullough, M. E., Tsang, J. A., & Emmons, R. A. (2004). Gratitude in intermediate affective terrain: links of grateful moods to individual differences and daily emotional experience. Journal of Personality and Social Psychology, 86(2), 295-309. doi: 10.1037/0022-3514.86.2.295