Gao Tianrui is from the United States. He moved to Beijing in 1995. Now, Gao Tianrui is working as a volunteer in Xicheng District of Beijing. His daily work is offering volunteer service to citizens and visitors with fluent Mandarin, and providing English training to other volunteers. Gao Tianrui enjoys voluntary work, and his favorite Chinese idiom is "助人为乐" (taking delight in helping others). "Such happiness occurs in me every single day," he said. Gao Tianrui has been witnessing the change of Beijing in recent decades. In his eyes, Beijing has changed from an ancient city to a world center with rapid growth. However, what attracts him the most is still the authentic and traditional part of Beijing.