New Delhi, Nov 22 (ANI): Tibetan spiritual leader, the Dalai Lama, urged the youth to preserve country's age-old tradition of religious harmony and tolerance, while delivering a lecture at a school in New Delhi on Saturday. Addressing the students, the Dalai Lama urged them to think cautiously not only about their own community or nation but humanity. He added that youngsters belong to the 21st century with their vision and determination can make a difference. Dalai Lama further said that past cannot be altered but future can be.