The story is that once a couple was travelling in a bus in a mountainous area .. at a place they decided and got down .. the bus then moved on .. after a few minutes a huge rock fell on the bus from the mountain .. and resulted in crushing and killing everyone in the bus .. The couple after knowing the accident, said - we wish we were on that bus .. further they added that If they had remained on the bus instead of deciding to get down .. the resulting time delay .. could have been avoided and the rock would have fallen after the bus had passed .. !!
Moral of the story - always think positive in life and look for the opportunities where you can help others ..