People walk around sad because they don't know what to do with their future. You have this minute right now. What are you going to do with it?
The difference between sadness and joy is very simple. Sadness always tells you: 'Oy vey! What are you doing to do in ten minutes? What will you do ten years from now?'
If you are really filled with joy for one minute, then you will know what to do the next minute also. What is G-d giving you? He is giving you this minute. He hasn't given tomorrow. Of course I don't know what to do tomorrow, because I didn't receive it yet.
Sadness is very much concerned with what I don't have, and I really don't have tomorrow yet. The truth is, I am always standing before nothingness, because I am nonexistent yet for the next minute. I'm not there yet. Time isn't there. The world isn't there!
The world is here...right now!
-- Rabbi Shlomo Carlebach, zt"l
BS"D - בסיעתא דשמיא