MANILA, Philippines -- Manny Pacquiao held back tears as he announced his retirement from boxing, after a professional career that spanned 26 years.

It was a day that Pacquiao "never thought" would come, as he closed the curtain on a legendary career that saw him win world titles in eight different weight divisions -- an unprecedented achievement that has yet to be matched.

• FULL STORY: Pacquiao retires from boxing, as he eyes presidency

He expressed his gratitude to those who introduced him to the sport, including his uncle Sardo Mejia who got him started in boxing. He called his longtime trainer, Freddie Roach, his family -- "a brother and a friend." Pacquiao was near tears as he paid tribute to his best friend, Buboy Fernandez, who has been in his corner for virtually all his life.

But the "Pacman" was most emotional as he officially bid goodbye to the sport that made him one of the most famous -- and richest -- athletes in the world, taking him from poverty into prominence and launching his political career.

"Goodbye, boxing," he said.

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Pacquiao's remarkable rise has been well-documented, in movies and TV shows and books. He left his hometown of General Santos as a teenager, moving to Manila to try to earn money to help his mother.

In his retirement speech, Pacquiao recalled that he dreamed of representing the Philippines in the Olympic Games, but was rejected by the national federation. He turned pro at the age of 16, but it wasn't until 2001 that Pacquiao truly emerged as a potential superstar, when he knocked out Lehlohonolo Ledwaba to win the IBF super bantamweight title as a late replacement.

From there, Pacquiao went on to fight -- and beat -- several all-time greats: Marco Antonio Barrera, Juan Manuel Marquez, Erik Morales, Oscar de la Hoya, and Miguel Cotto. His May 2015 fight against Floyd Mayweather Jr., though long delayed, became one of the most lucrative events of all time.

Boxing, Pacquiao said, changed his life.

"When my family was desperate, you gave us hope. You gave me the chance to fight our way out of poverty. Because of you, I was able to inspire people all over the world," he said.

"Because of you, I have been given the courage to change more lives. I will never forget what I have done and accomplished in my life," he added.

His final match came in August, against Cuba's Yordenis Ugas. Pacquiao, in a way, came full circle: he first made his name as a replacement fighter when he dethroned Ledwaba in 2001, and his career ended against Ugas, who replaced American Errol Spence Jr. some two weeks before the bout.

Pacquiao, coming off a two-year layoff, could not put together the same explosiveness and intensity that he had in previous fights, and Ugas was the clear winner of their encounter. The "Pacman," afterward, was gracious in defeat, and grateful to the Las Vegas crowd that cheered for him all night long.

On Wednesday, Pacquiao said that he has "just heard the final bell."

"Tapos na ang boxing," he said, again looking as though he was holding back tears.

As he steps away from the sport, Pacquiao shifted the focus to the country's up-and-coming boxers. Even before his retirement, Pacquiao has already put together a strong stable of fighters in his promotional outfit, MP Promotions, which features Olympic bronze medalist Eumir Marcial, and world champions Jerwin Ancajas and John Riel Casimero.

"Napakarami nating mga mga potential boxers na mas bata at puno ng pag-asa na makapagdala ng karangalan sa ating bansa," said Pacquiao. "Sila naman po ang ating tulungan."

His full attention, now, is on his political career. Pacquiao announced two weeks ago that he is running for president in the national elections next year.

"I am a fighter and I will always be a fighter inside and outside the ring," Pacquiao said after accepting nominations from around 20 PDP-Laban chapter leaders last Sept. 19 at their national assembly in Quezon City.

• READ: Pacquiao accepts PDP-Laban faction's nomination, launches 2022 bid for presidency