Pope Benedict XVI said he has faced moments of "joy and light" but also "difficult moments, choppy seas and headwinds" during his final speech before abdicating.
Nearly 200,000 pilgrims gathered in St Peter's Square to witness Joseph Ratzinger's valedictory address on the eve of his resignation from the papacy.
"I thank you for having come in such a great number. I'm frankly moved," Benedict told the huge crowd.
The Pontiff said he decided to put an end to his near eight-year papacy because, over recent months, he felt his "strength has decreased."
"I asked God to light the way for me to make the right choice, not for my own good but for the Church's," he added.
Benedict arrived in St. Peter's square surrounded by bodyguards aboard an open-sided white 'Popemobile' which slowly made its way through the crowd to give every attendant a glance of the first Pope to abdicate since the Middle Ages.
The Pope's general audience usually takes place inside the Vatican but was moved outdoors because of the huge number of people expected to attend.
Benedict compared his papacy to a gospel passage in which St. Peter set sail on a boat with the apostles over the Galilee Lake.
"There have been good fishing days as well as difficult moments, choppy seas and headwinds and it seemed that the lord was sleeping," Benedict said, as his voice was often interrupted by the thunder of applause.
"But I've always known the Lord was there and would have never let the boat sink."
Benedict also dismissed recent reports of in-fighting within the Holy See, publicly thanking Secretary of State Tarcisio Bertone, with whom he was rumoured to be at odds, for "having faithfully accompanied me throughout the papacy."
The Pope said that, since he accepted the chance to assume the Petrine ministry, he has had "no privacy."
"Life has been deprived of its private dimension," he said. "I didn't belong to myself anymore but to everybody."
However Benedict said he does not intend to retire from public life, insisting: "I will not abandon the cross. I am to remain alongside the Lord crucified, in the service of praying."
Finally Ratzinger asked devotes to pray for the cardinals called to elect a new Pope and for his successor.
The 85-year-old will keep his papal name and the title of 'His Holiness' upon his resignation, which is due tomorrow. He will thereafter be known as 'Pope Emeritus'.