KRAKOW, Poland— Pope Francis comes most alive when he gets to be a pastor, and on Thursday he got to be just that, delivering a simple yet powerful message to the hundreds of thousands of young women and men who travelled to the land of St. John Paul II to participate in World Youth Day.

His message to them? “Don’t throw in the towel.”

“It pains me to meet young people who seem to have opted for ‘early retirement’,” the pope said. “I worry when I see young people who have ‘thrown in the towel’ before the game has even begun, who are defeated even before they begin to play, who walk around glumly as if life has no meaning,” Francis said.

After more than 24 hours in Krakow, Francis “at last” met those who he’d come here to see: the young pilgrims who travelled from 187 countries.

Addressing the hundreds of thousands gathered in Krakow’s Blonia Park, the pope also said that there are many young people who “waste their lives looking for thrills or a feeling of being alive by taking dark paths and in the end having to pay for it… and pay dearly.”

Going off the cuff, which he did at several points of his address, he said “I’m sure that among you there’s no one like this. But there are young people who’ve retired, who give up before the game, young who enter the vertiginous of fake illusions and end up in nothing.”

Francis is currently visiting Poland for World Youth Day (WYD), a week-long celebration that takes place every two or three years in different countries, the closest thing to a religious Woodstock. Over the years, close to 17 million people have taken part in them.

Pope Francis waves to a cheering crowd of faithful as he drives by in a public transportation tram he used to reach the venue of the World Youth Days in Krakow, Poland, Thursday, July 28, 2016. Pope Francis is in Poland for a five-day pastoral visit and to attend the 31st World Youth Days. (Stefano Rellandini/Pool photo via AP)
Pope Francis waves to a cheering crowd of faithful as he drives by in a public transportation tram he used to reach the venue of the World Youth Days in Krakow, Poland, Thursday, July 28, 2016. Pope Francis is in Poland for a five-day pastoral visit and to attend the 31st World Youth Days. (Stefano Rellandini/Pool photo via AP)

Francis arrived to the downtown park in a “Cracovian,” one of the 36 trams Poland bought last year, all street-level vehicles adapted to the needs of the handicapped. During the short trip from the bishop’s residence where Francis is staying during his July 27-31 visit, Francis was accompanied by disabled pilgrims and their caregivers.

Once in Blonia Park, the pope did the mandatory swing in the Pope-mobile, blessing screaming pilgrims left and right, who welcomed him with singing, shouting and a general atmosphere of hysteria.

Once he arrived on the stage, a smiling Francis was welcomed by Cardinal Stanislaw Dziwisz of Krakow and several dozen dancers who performed musical pieces representing the various continents, including an Argentine tango in honor of history’s first pope from the global south, giving the opening ceremony an atmosphere similar, though less expensive, to that the Olympic Games.

Among other things, Francis received a specially made pilgrim backpack, similar to the one of the over 350,000 registered pilgrims received, but in white to match the papal dress etiquette.

Earlier in the day, he celebrated Mass for hundreds of thousands in the Jasna Gora monastery, Poland’s most famous pilgrimage site, visited by an estimated four million people each year. There, more than 300,000 people waited for him under the rain, many of them overnight.

“Your own history, shaped by the Gospel, the Cross and fidelity to the Church, has seen the contagious power of a genuine faith, passed down from family to family, from fathers to sons and above all from mothers and grandmothers,” the pope said in his homily at the shrine of the Black Madonna of Częstochowa.

A big portion of his homily, however, was dedicated to the Virgin Mary, who Francis described as “the stairway God took to descend and draw near to us.”

It’s in the life of Mary that the “littleness that God loves” becomes evident, because he “looked upon the humility of his servant”, and “lifted up the lowly”

As it was to be expected, the looming figure of his predecessor, St. John Paul II, has been omnipresent during the first 24 hours of Francis’ visit to Poland: From banners in the streets to stickers on buses and portraits carried by the pilgrims, the patron of WYD was everywhere.

Including, of course, in Francis’s addresses.

In the one he gave in the afternoon, the pope thanked John Paul for creating these youth events that have been taking place since the mid-1980s in different cities, from Buenos Aires in 1987, through Manila, Santiago de Compostela, Madrid, Denver, Sydney, Toronto and Rio de Janeiro.

“From his place in heaven, he is with us and he sees all of you: so many young people from such a variety of nations, cultures and languages but with one aim, that of rejoicing that Jesus is living in our midst,” Pope Francis said.

Tying WYD to the Holy Year of Mercy, the pontiff said that during these days Poland wants to be “the ever-youthful face of mercy.”

“From this land, with you and all those young people who cannot be present today yet join us through the various communications media, we are going to make this World Youth Day an authentic Jubilee celebration,” Francis said.

As he often does when he talks to youth, the pope spoke about his experience as Archbishop of Buenos Aires. This time, he said that during those years he learned that nothing is more beautiful than “seeing the enthusiasm, dedication, zeal and energy with which so many young people live their lives.”

“When Jesus touches a young person’s heart, he or she becomes capable of truly great things,” he said.

After inviting the thousands not to let anyone convince them they can’t change reality, he went off the cuff, adding that there are some who want to convince the youth that things cannot be fixed. “I ask you … Can things be changed?”

To which the crowd responded with a resounding “Yes!”

During his remarks, Francis also touched on the issue of immigration, seeing that in many ways these international youth gatherings provide a unique opportunity to provide a human face to what’s considered the worst refugee crisis since WWII.

“A merciful heart is able to be a place of refuge for those who are without a home or have lost their home; it is able to build a home and a family for those forced to emigrate; it knows the meaning of tenderness and compassion. A merciful heart can share its bread with the hungry and welcome refugees and migrants,” he said.

To say the word “mercy,” Francis continued, is to talk about “opportunity, future, commitment, trust, openness, hospitality, compassion and dreams.”

In a playful mood, several times the pope interacted with the crowd, asking them to respond to things such as, “Can we buy Jesus? Is he sold in the stores?”

Francis closed his remarks asking the youth to join him in prayer, asking God to “launch us on the adventure of mercy!” of building bridges and tearing down walls, barriers and barbed wires – a clear reference to the many fences being built across some European countries to keep migrants out.

“Launch us on the adventure of helping the poor, those who feel lonely and abandoned, or no longer find meaning in their lives,” he said.