Pope John Paul II marked the 24th anniversary of the start of his papacy with a prayer for strength Wednesday, asking the Virgin Mary to help him continue in his mission.

Tens of thousands of pilgrims cheered, waved Polish flags and held up white handkerchiefs as the 82-year-old pope was driven into St. Peter's Square.

He announced he was making changes in the Rosary, a series of prayers said by Catholics using sets of beads, signing the document as he sat on the steps of St. Peter's Basilica. He also announced the beginning of the Year of the Rosary.

In making the changes to the Rosary, John Paul said recently that he wanted Catholics to "rediscover the beauty and depth of this prayer."

The frail pope, who has repeatedly brushed aside reports that he might step down, recalled words said during his August trip to Poland, when he asked the Virgin Mary for the strength "in body and spirit" to continue his mission "until the end."

"I repeat those words today, giving thanks to God for the 24 years of my service to the Church in the See of Peter," he said. "I once again entrust to the Blessed Virgin my future."

He is already one of the longest serving popes in history and has outlived many of those seen as possible successors.

"It's the start of the 25th year of John Paul's pontificate," the Vatican newspaper L'Osservatore Romano declared in a special edition, as if to emphasize the pope's resolve.

The day was a Vatican holiday, but his fellow Poles were planning to mark the occasion by serenading below his window in St. Peter's Square, and John Paul went ahead with his regular general audience.

The Vatican issued a spate of statistics to underscore the records of his papacy — including 98 foreign trips covering 742,020 miles, elevating 464 saints and holding 1,430 audiences and meetings with political leaders.

Only four popes have served longer than John Paul, and he is closing in on two of them. By Vatican count, the record is held by St. Peter, the first pope, listed as serving either 30 or 37 years.

The pope is frail, suffering from the symptoms of Parkinson's disease, as well as knee and hip problems. Vatican officials improvise to accommodate his ailments, now wheeling him around during public appearances on a cart-like vehicle.

Although a proposed trip to the Philippines in January has been ruled out, a sign that John Paul is slowing down, Vatican officials insist that the most traveled pope in history will continue foreign pilgrimages with a visit to Croatia next spring.