As Shimon Peres turns 90, the indefatigable Israeli president is doing what he has always done: looking ahead, preparing for the next challenge and believing that he will see Middle East peace in his lifetime.

Old age has hardly slowed him down. If anything, it seems to have handed Peres a measure of the grace that eluded him as a younger man. And at a time when Israel is widely criticized for its ongoing occupation and continued settlement of war-won land, he operates as something of a one-man reminder that the country once aimed _ in its 1948 Declaration of Independence _ to be a "light unto the nations."

"For me, what is important is tomorrow, the next day. What happened until now is over, unchangeable. I'm not going to spend time on it. So I am really living in the future," said Peres in an interview with The AP. "I really think that one should devote his energies to make the world better and not to make the past remembered better."

Peres seemed energetic and spiffy in a dark suit and purple tie as he sat in his office, whose book-lined shelves include three devoted entirely to his own works, in Hebrew and myriad translations. The mention of old age seemed to deeply startle him, as did any notion of retirement or even vacation, which he dismissed as a "waste of time."

On Tuesday, Peres launches a three-day event called the "President's Conference" _ an annual gathering of artists, thinkers and leaders whose global guest list reflects an extraordinary profile on the world stage: More than any other prominent Israeli politician he seems to largely be forgiven for his country's extremely messy conflict with the Palestinians.

A politician of astounding longevity _ he was a young aide to the country's founding father David Ben-Gurion at the time of independence in 1948 and a top defense official in the 1950s _ Peres has nonetheless been strangely unsuccessful for much of his career. Despite having slipped into the prime minister's post three times over the years, each tenure was short-lived. He never won an election outright, losing outright four times and tying once, earning a reputation as a grasping manipulator who was also a bit of a schlemiel.

His propensity for aphorism _ "You can make omelets out of eggs, but not eggs out of omelets!" _ has befuddled many a campaign crowd. And the distinctive cadence, which to this day betrays his Polish roots, is still a mimic's delight. An unbending belief in peace has been taken by many Israelis as dangerous naivete. And it is ironic as well: Peres was once something of a security hawk, and he is widely credited with engineering, a half century ago, Israel's status as a nuclear power.

It took a meltdown by his predecessor in the mostly ceremonial president's role for Peres to finally win the recognition he had coveted for so many years. Caught up in a devastating sex scandal, Moshe Katsav was forced to step down in 2007 to face rape charges. Seeking to stabilize the cherished institution, parliament turned to Peres and elected him president. Katsav was convicted and is now in prison.

Peres, 83 at the time, seemed to benefit simply by not being the tongue-tied Katsav. Statesmanlike and serious, supposedly above politics in his new role, his popularity skyrocketed among Israelis at last.

Peres has used the presidency to speak out as a voice of reason on political affairs, cautioning political leaders against attacking Iran's nuclear program last summer, and packaging himself as a lovable grandfatherly figure. He has embraced Facebook and frequently meets with children and young Israelis.

"Shimon Peres has undergone a miraculous transformation which almost all politicians in the world would love to experience," said Israeli historian Tom Segev. "For most of his public life, he was the most hated politician in Israel. He was the symbol of petty, dirty politics. Since he became president almost all of a sudden his people began to love him. It's almost like a fairy tale."

Peres attributed the stunning turnaround to the power of the presidency. Freed from the constraints of political intrigue, "all of a sudden I discovered I don't need power. ... But if (the people) think that I came to serve, they will trust (me) and I could have achieved many things that maybe in the government I wouldn't be able to do."

A poll in March published by the Haaretz daily showed Peres with a 74 percent approval rating, far ahead of conservative Prime Minister Benjamin Netanyahu, at 48 percent. The poll, conducted by the Dialog agency, questioned 473 people and had a margin of error of 4.6 percentage points.

On the international front, Peres probably benefits similarly by not being Netanyahu. Now in his third term, Netanyahu is seen as a peace skeptic with a hard edge, and a world eager to put the Israeli-Palestinian conflict to bed generally does not admire his continued building of Jewish settlements in the occupied West Bank.

Peres is the Israeli leader many in the world would far prefer: conciliatory, philosophical and seemingly amenable. He never tires of the promotion of peace and seems genuinely driven by a vision of a better world.

During the interview, Peres declined to criticize Netanyahu directly, noting that Netanyahu has in principle accepted the "two-state solution" but allowing that he would like progress toward the establishment of a Palestinian state to be "faster." Negotiations are currently on hold _ as they have been, mostly, since Netanyahu's return to office in 2009, with the Palestinians insisting in vain on a settlement freeze and Israel refusing "preconditions."

Peres seems at pains to not betray frustration the government's policies, including its apparent ignoring of the recently-reissued Arab League initiative offering regional peace in exchange for a pullout from the land Israel captured in the 1967 war. He noted that the offer was at least not rejected outright.

Peres said that despite all the failures in peace efforts over the years, he looks at the successes: a historic agreement with Egypt in 1979, peace with Jordan in 1994 and interim accords with the Palestinians in the 1990s.

"That gives me the license to be an optimist, and I would never give up this license," he said. "I'm sure I shall see peace in my lifetime. Even if I should have to extend my life for a year or two, I won't hesitate."

Yossi Beilin, a former protege who served as Peres' deputy at the Foreign Ministry in the 1990s, said the move into the presidency was "a very important strategic decision" for his onetime mentor. "I think he is enjoying very much, for the first time in his life, a situation where everybody likes him ... This is his retirement."

Peres has become a fixture at a variety of annual international events like the World Economic Forum in Davos, Switzerland, showing up each year to a kind of reverent acclaim enjoyed by only a tiny handful in the world.

This year he was awarded the central onstage interview with Davos founder Klaus Schwab, who respectfully queried him on subjects as diverse as the Arab Spring and the nature of the modern multinational corporation. Last summer at the similar Ambrosetti Forum in Italy, Peres held an audience of high-powered officials and businesspeople rapt with his musings on the workings of the human brain.

In Jordan last month, Peres was enthusiastically received by clapping, whistling business leaders from around the Arab world. His call for new peace talks drew several standing ovations from an audience of 2,000 that included U.S. Secretary of State John Kerry, Jordan's King Abdullah II and Palestinian President Mahmoud Abbas.

"He is a man of peace," said Palestinian business tycoon Munib Masri, who was in the crowd. "People see him that way and like him for that." He then embraced King Abdullah, tapped him on the shoulder as both exchanged smiles and warm greetings.

Back home, some criticized him for pushing the limits of what is supposed to be an apolitical office. "I didn't know that Peres became the government spokesman," said Cabinet minister Yuval Steinitz.

The birthday celebrations have also come under fire for extravagant spending, including a $500,000 fee for an appearance by Bill Clinton at a college, and a $3 million budget for the conference itself. Organizers have said the funding has come from private donations, not public money. Clinton subsequently donated his speaking fee back to the Peres Academic Center, the college where he spoke, for student scholarships.

But Peres seems to be revered by his staff. His chief of staff, Efrat Duvdevani, sparked a debate at home this week by leaving her hospital room, hours after giving birth, to return to work ahead of the conference.

Peres established the conference soon after taking office as president in 2008 as a sort of mini-Davos, attracting top scientists, philosophers and business leaders. It is an ambition that is hard to imagine elsewhere, or being attempted by any successor.

Yet it works: This year's guest list includes Clinton, Tony Blair, Rahm Emanuel, and Larry Summers _ as well as Robert DeNiro, Sharon Stone and Barbra Streisand. The gathering is also serving as a birthday party for Peres, who turns 90 in August.

Peres seemed pleased and embarrassed when asked about the unlikely rock-star status he has cultivated late in life. "I think it's a God-sent opportunity for a human being like myself to have the occasion to serve the people sincerely with love and hope," he said.

With just one year left in his presidency, Peres rules out running for elected office but says he has no plans to retire and will search for new ways to serve the people _ and also to spread "tranquility" around the world.

"I am not running for anything and I am not running away from anything," he said. "I am trying where I can to be a unifier, to unite. When I have to voice my view I do, and I shall continue to do it."

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Dan Perry has covered the Mideast since the 1990s and currently leads AP's coverage in the region. Follow him at twitter.com/perry_dan

Josef Federman is the Associated Press News Editor for Israel and the Palestinian territories. Follow him at twitter.com/joseffederman.

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Associated Press writer Max J. Rosenthal contributed to this report.