YINCHUAN, Aug. 7 (Xinhua) -- At 57, retiree Chen Jinfeng has discovered a new sense of purpose after retirement. Much of her day is spent lending a hand to neighbors as a volunteer and making a difference in the lives of those around her. On a quiet evening, Chen gently knocked on an elderly resident's door. "There will be a free health checkup tomorrow morning. Remember, no breakfast beforehand," she reminded th