LISBON, Portugal (CNS) -- After many of the 1.5 million young people gathered in Lisbon's Tejo Park waited for hours in near 100-degree weather to participate in the World Youth Day vigil with Pope Francis Aug. 5, the pope asked them, "Have you ever been tired?"

Even when tempted to "throw in the towel" or stop along the journey of life, the pope said, the young people must pick themselves up and walk toward joy.

"Joy is not hidden, it's not kept under key, we have to look for it," he said, "and that is tiring."

Yet, Pope Francis urged them to "rise up" when they fall along the path toward joy.

Before the pope's improvised speech, synchronized drones flew over the massive crowd, which extended across both banks of Lisbon's Trancão River, forming messages that read "Rise Up" and "Follow Me" in different languages.

After a lengthy tour in the popemobile among the pilgrims, Pope Francis listened to two testimonies from people who talked about how their experience of faith formed their youth. Marta Luis, 18, from Mozambique, told Pope Francis how her home province had been ravaged by a civil war and how her family had to leave her village due to a terrorist attack.

While they were sleeping in a forest after they left their home, "we didn't sleep the whole night, but we prayed the Hail Mary and the Our Father," before trekking to another province where they reached family members and were taken in by a local parish.

"Amid so much suffering, we never lost the faith and hope of rebuilding our life," she said.

Pilgrims had begun filling the park in the morning. Many young people waited as much as nine hours to see the pope, but they remained in high spirits playing games, singing songs and doing the occasional wave.

"Sunscreen and water" were the keys to resisting the Lisbon sun, said Mary Grace Quinlan, 28, from Missouri, who was among the first lined up to see the pope. She told Catholic News Service she was struck by the pope's message during the official welcome ceremony for World Youth Day when he urged young people to know each other by their names and not only their virtual or online personalities.

Almost all the pilgrims near the stage planned to spend the night in the park to save their spots for the papal Mass the following morning. They sprawled across the park on yoga mats and inflatable camping mattresses, some in tents or under makeshift cover from tarps.

After the pope's speech, the 1.5 million people in the park fell into silence for eucharistic adoration, hymns of praise and benediction.

Only reading the first few words of his prepared remarks, Pope Francis put down the text in his hand and spoke openly with the young people.

"Do you like soccer?" he asked the audience to a loud applause. "I like it," he said with a smile, noting that "behind every goal there is much training, behind each success there is much training, and what can I do in life? Train myself."

But the pope added that "there isn't any course on learning how to walk in life," but rather that its learned from parents and grandparents, teachers and friends.

Pope Francis urged the young people to look within themselves and find the "roots of joy" that exist within them, roots planted by the people who have touched their lives.

"We come from roots of joy, and we can be roots of joy for others," the pope said. "Not a joy of the moment, but a joy that gives roots."