你快乐，所以我快乐...

when i was 15, this statement for me meant: when you laugh, i will laugh (as we are happy)...

when i was 20, this statement meant when i know you are happy, i will be happy; we are together and i can "feel" your mood.

and now, i realised it can be even different... the statement means: when you are happy, i am happy too, even we are no longer together, or even we are no longer friends, but when i know you are happy, i will feel happy, and i am happy for you...

time has made us become wiser and better in terms of thinking and transforming...
we mature a lot while we experience different problems, hardship, and stages in life...
we learn not to escape from reality when there are difficulties and imperfection;
we learn how to adapt to changes in life when that is a must;
we learn to care about other's feeling and be happy when somebody else is...

you are happy and thus i am happy too...