Story highlights "You made me a better President, and you made me a better man," he wrote

The letter highlights memorable highs and lows of the last eight years

Washington (CNN) President Barack Obama penned an emotional public letter, published Thursday, thanking Americans and encouraging them to participate into "daily acts of citizenship."

"Before I leave my note for our 45th president, I wanted to say one final thank you for the honor of serving as your 44th," he wrote. "Because all that I've learned in my time in office, I've learned from you. You made me a better president, and you made me a better man."

The President recalled tragedies such as the Charleston church massacre and celebrations such as military graduations. He also celebrated gay and lesbian Americans who now have their marriages recognized and ill people who now have access to health care.

Obama went on to challenge voters -- regardless of political affiliation -- to commit themselves to improving the common good.

"I've seen you, the American people, in all your decency, determination, good humor and kindness. And in your daily acts of citizenship, I've seen our future unfolding," he said. "All of us, regardless of party, should throw ourselves into that work -- the joyous work of citizenship. Not just when there's an election, not just when our own narrow interest is at stake, but over the full span of a lifetime."

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