From : http://en.wikipedia.org/wiki/Gratitude

Gratitude, appreciation, or thankfulness is a positive emotion or attitude in acknowledgment of a benefit that one has received or will receive.

Psychological research has demonstrated that individuals are more likely to experience gratitude when they receive a favor that is perceived to be (1) valued by the recipient, (2) costly to the benefactor, (3) given by the benefactor with benevolent intentions, and (4) given gratuitously (rather than out of role-based obligations) (e.g., Bar-Tal, Bar-Zohar, Greenberg, & Hermon, 1977; Graham, 1988; Lane & Anderson, 1976; Tesser, Gatewood, & Driver, 1968). Individuals who are induced to feel grateful are more likely to behave prosocially toward their benefactor (Tsang, 2006b) or toward unrelated others (Bartlett & DeSteno, 2006).

Although gratitude is something that anyone can experience, some people seem to feel grateful more often than others. People who tend to experience gratitude more frequently than do others also tend to be happier, more helpful and forgiving, and less depressed than their less grateful counterparts (Kashdan, Uswatte, & Julian, 2006; McCullough, Emmons, & Tsang, 2002; Watkins, Woodward, Stone, & Kolts, 2003)

Remind me to always say “Thank You” to anyone who has give me help in my life. Just two simple word “Thank You” but a big meaning behind it.

Thank you to Mr. William Fan who has teach me