The US leader is famous of his aura of unflappability in the face of crisis, but he acknowledged that there are sometimes roiling emotions beneath the surface.
"I have a confession to make. There are times when I'm not so calm. My wife knows. There are times when progress seems too slow. There are times when the words that are spoken about me hurt. There are times when the barbs sting. There are times when it feels like all these efforts are for naught," he added.
"Change is so painfully slow in coming. And I have to confront my own doubts."
But the president said it was his faith that gave him inner calm and peace and urged congregants at the church to find solace in theirs.
"So let us hold fast to that faith," Obama urged the congregation.
"Together, we shall overcome the challenges of the new age. Together, we shall seize the promise of this moment. Together, we shall make a way through the winter. And we're going to welcome the spring."
Obama, the nation's first African-American president, spoke on the eve of the Martin Luther King Jr holiday. During the service, where his two daughters and his wife joined him, he nodded his head and tapped his feet as the choir sang.
Reverend Cornelius Wheeler said the church had already sent 2,500 dollars in aid to quake-devastated Haiti.
The massive hope and goodwill that greeted Obama's historic inauguration have partly evaporated, with the change he promised neither as fast nor as sweeping as had been expected in the face of challenging times.
Despite some successes, Obama now confronts a thicket of domestic and foreign challenges, among them a ballooning deficit, 10 percent unemployment, approval ratings tipping below 50 percent, revived fears of Al-Qaeda airborne terror and an emboldened insurgency in Afghanistan.
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