Pop superstar Christina Aguilera struggled to contain her emotions during a recent charity trip to a Rwandan refugee camp, insisting it was "one of the most difficult moments" of her visit. The Beautiful hitmaker travelled to the war-torn nation in June (13) in her role as a spokesperson for Yum! Brands' World Hunger Relief effort, and she spent some of her time meeting those battling severe poverty and serving food to children. The mum-of-one admits the tour of Rwanda really opened her eyes and made her more determined to speak out to draw attention to the extent of the hunger problems suffered around the world. She tells the Associated Press, "It's so sad to think there's nothing that sets any of us apart. And when you go into the field, you really see that and feel that we're all one in the same, it's just we're born under different circumstances, and it's sad and I don't understand why, but I feel what I feel and I did what I can." Aguilera was particularly moved by her visit to a refugee camp, which she claims was "one of the most difficult moments" of the mission. She adds, "They had to escape everything and everybody they knew and loved, and it's just a lot to really open yourself up and feel all that. And you just want to help out in whatever way that you can, and obviously I get emotional about it when talking about it, but I think it's important to feel those things." The singer appears in a new public service announcement (PSA) for the World Hunger Relief campaign, which features her song Light up the Sky.