I get these inspiring thoughts that just pop into my head from time to time and want to put this one into words. It is about being happy for others, be it your friend, relative or some one at work:
Be happy for others NOW, because their happiness may not last...
Be happy for one's self NOW, because your happiness may not last
It is so because the world we live in, nothing is permanent. This may sound a bit harsh, but the sooner we come to terms and accept the impermanence of all thoughts, phenomena and feelings, the sooner we can just "live in the moment" and find a deeper peace.