Sonu Nigam sings it well too...
Har ghadi badal rahi hai roop zindagi
Chaav hai kabhi kabhi hai dhoop zindagi
Har pal yahan jee bhar jiyo
Jo hai sama, kal ho na ho
Life changes its expression constantly,
At times gloomy, at times sunny,
Live every fraction of time to the fullest,
For this moment today may or may not be there tomorrow.
So why worry today...tomorrow might not even come!LOL
Note: I did not do a word to word translation..I translated the gist of the stanza rather than going word for word which most online translations do.