Former US President Barack Obama expressed frustration with the latest effort by Republicans to limit health care access during an event hosted by the Gates Foundation earlier today.

“When I see people trying to undo that hard-won progress for the 50th or 60th time with bills that would raise costs or reduce coverage for older Americans or people with preexisting conditions — the cancer survivor, the expecting mom, or the child with autism or asthma, for whom coverage would once again be unattainable,” he said. “It is aggravating.”

“And all of this being done without any demonstrable economic or actuarial or plain common sense rationale, it frustrates,” he added. “And it’s certainly frustrating to have to mobilize every couple of months to keep our leaders from inflicting real suffering on our citizens.”

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Obama was speaking at Goalkeepers, an event organized by the Gates Foundation to accelerate world progress on the United Nation’s Global Goals.

He addressed a room full of activists from around the world, and he used his time to encourage them to stay optimistic while confronting the world’s problems.

“Despite the naysayers and cynicism, progress happens,” he said. “It’s not the result of chance, it’s because countless people like you, toiling for many years, chose to make this progress.”

The former president reminded the audience to consider the long arc of progress throughout history.

Over the past century, he said, nearly all women have gained the right to vote, life expectancies have risen by decades, maternal and child mortality rates have plummeted, education levels have soared, and violence has dropped to historic lows.

“All of this has happened in such a steady march that sometimes we have a tendency to take it for granted,” he said.

“Some people like Bill and Melinda have enormous wealth and influence, others like Trudeau have formal political offices, but the majority of people who made these advances were citizens, doctors, nurses, entrepreneurs, clergy, moms, community leaders, activists, union leaders, who mobilized and organized and voted and innovated and pushed for change,” he said.

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During the event, which runs concurrently with the UN General Assembly, Obama alluded to his successor, US President Donald Trump, when voicing support for multilateral institutions.

“The biggest problems we confront — no one nation will be able to solve them on its own, not even a nation as powerful as the US,” Obama said.

On Tuesday, President Trump lamented what he saw as the burden imposed upon the US by the UN, and called on countries to put their own citizens first. To underline his point, Trump said the word “sovereignty” 20 times in 40 minutes.

“Multilateral organizations are important,” Obama said. “And you don’t have to cede your sovereignty or it doesn’t make you less patriotic to believe that, you just have to have some sense and read.”

Ultimately, however, Obama used the occasion to avoid partisanship, returning to common themes of his presidency when he called for unity and common cause.

He commended former President George W. Bush on creating the President's Emergency Plan for AIDS Relief (PEPFAR).

“What his administration initiated with PEPFAR was a singularly important achievement that we needed to sustain and build on,” he said.

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Foreign aid, according to Obama, seemed to be the one topic that US politicians universally supported because of the returns on investment that it generates. He pointed to how bolstering foreign governments reduces conflict, how addressing the causes of famine reduces mass migration, and how investing in girls’ education builds robust trading partners.

These advances all ultimately end up benefitting the US, he said.

The Trump administration has proposed cutting foreign aid spending by 32% for 2018, a decision that would imperil millions of lives around the world.

Global Citizen is campaigning to #StopTheCuts, and you can take action on this issue here.

Obama, too, called for robust international assistance and encouraged the audience to take leadership on the issue.

“Reject cynicism and reject pessimism,” he said. “Push forward with a certain infectious and relentless optimism, not blind optimism, not one that ignores the scale and the scope of challenges, but hard-earned optimism that’s rooted in the stories of the very real progress that has occurred throughout history.”

“What a glorious thing it is, to be responsible for saving the world.”

Disclosure: The Bill and Melinda Gates Foundation is a funding partner of Global Citizen.

Editor's note: This piece has been updated to include a disclosure that the Bill and Melinda Gates Foundation is a funding partner of Global Citizen. We regret the oversight.