Flash mobs are nothing new, but the sweet story behind this one will definitely pull at your heartstrings. Since 2012, a woman named Amy has been battling ovarian cancer, and in October, she received a terminal diagnosis. Last weekend, Amy's daughter organized a surprise party for her 56th birthday, leading Amy into the backyard as the song "Best of My Love" started to play. Soon Amy's loved ones started to flood into the yard. As 50 of her friends and family members danced together, Amy laughed and clapped along. Watch the heartwarming video above, then check out more can't-miss viral videos!