VATICAN CITY -- Pope John Paul II marked the 24th anniversary of the start of his papacy by praying for strength.

He's asked the Virgin Mary to help him continue his mission. The 82-year-old pontiff said he thanks God for his 24 years of service.

Tens of thousands of pilgrims cheered, waved Polish flags and held up white handkerchiefs as the pope was driven into St. Peter's Square.

John Paul is one of the longest-serving popes -- outliving many of his possible successors. He's repeatedly brushed aside reports he might step down.

The pope also announced he's making changes in the Rosary, a series of prayers said by Catholics using sets of beads.