Pope Francis tossed aside his prepared remarks in a talk to thousands of Paraguay's young people – urging the crowd to go against the cultural current and to live for Jesus with a "free heart."

"I wrote a speech for you, but prepared speeches are boring," the Pope said as cheers erupted from the scores of young people who packed the "costanera" or beach front of the Paraguay river in Asuncion.

The inland nation is the last of the three stops on the Pope's trip to South America. He visited Ecuador July 5-8 and spent a few days in Bolivia before heading to Paraguay on July 10 to finish his visit.

"We don't need young people who waste their lives," he said enthusiastically. "We need young people with hope! Because they know Jesus and they have a free heart."

The idea of a liberated heart was central to the Pope's address.

"Liberty is a gift that God gives us, but we must know how to receive it. We must have a free heart," he said.

"Hunger, drug addiction, sadness: all of these things take our freedom from us," he lamented, leading the young people present in praying for a transformed heart.

"Lord Jesus, give me a free heart that is not a slave to any evil in the world, that is not a slave to the community, that is not a slave to a comfortable life, that is not a slave of vice, that is not a slave to a false liberty that is the desire to do whatever we want, whenever we want to do it," he prayed.

Much of the Pope's off-the-cuff remarks came in response to the stories shared by young people present at the event.

One young woman, Liz, offered her testimony of caring for her mother, who has dementia and believes herself to be her daughter's child.

The Pope noted that Liz, while saddened by the sickness of her mother, drew strength from her aunt and a community of young people.

"This is what we mean by solidarity," he said.

Pope Francis also responded to the testimony of Manuel, who described growing up in poverty and being taken to the city, where he was exploited and beaten as a worker, fell into the trap of addiction, and eventually found support in a parish group.

Manuel's life was not easy, the Holy Father said. "But instead of taking the wrong path, he went to work. He didn't try to steal, even in his conditions. He is trying to go forward."

Like Liz and Manuel, he continued, we can all draw strength and hope from knowing Christ. He encouraged gratitude among those who live comfortably, with the opportunity to eat every day and pursue studies.

"If your life is easy, there are others for whom it is not easy," he said, reminding them to reach out and say to their struggling brothers and sisters, "We are here. We are with you. We want to give you hope."

Pope Francis concluded with a call for the young people to "go against the current" and follow the path of Christ, not being afraid to dream big and "make a mess."

"Keep making noise," he said.