Extending greetings to the doctors on Doctors' Day, Haryana Chief Minister Manohar Lal Khattar on Friday said that serving the poor people as a mission is the biggest service to humanity. In a message issued here today on the occasion of National Doctor's Day, the Chief Minister said, “In today's era everyone has joined the rat race. Now we have to pay attention to the health of environment along with the health of human beings. We have to change our eating habits. For which only a doctor can give the right advice.”