VIDEO : Madonna Says Motherhood Is Her Biggest Challenge

Madonna received Billbord magazine's Woman of the Year award on Friday. The seven-time Grammy award winner said that her biggest challenge has been being a good mother. Madonna, who is 58-years-old, has four children. In March she completed an 82 show "Rebel Heart" world tour. She's currently in a custody battle with her ex-husband Guy Ritchie, over their 16 year-old son Rocco. During her tour, Rocco left Madonna to live with Ritchie in London.