US President-elect Barack Obama forewarned Americans of the tough days ahead and said that meeting the challenges being faced by United States, specially the economic crisis, is not going to be easy. Addressing a mammoth crowd, who braving severe cold gathered for the star-studded inaugural celebration at the historic Lincoln Memorial on Sunday, Obama listed out major challenges being faced by the US. Country's top musical stars including Bruce Springsteen, Shakira, Garth Brooks, Bono and Stevie Wonder enthralled the audience with their inspirational performances. The future First Family was seated in a secure enclosure enjoying the music. "I won't pretend that meeting any one of these challenges will be easy. It will take more than a month or a year, and it will likely take many. Along the way, there will be setbacks and false starts and days that test our resolve as a nation," Obama said. Addressing the cheering crowd, Obama said in the course of US history, only a handful of generations have been asked to confront challenges as serious as the ones being faced right now. "Our nation is at war. Our economy is in crisis. Millions of Americans are losing their jobs and their homes. They're worried about how they'll afford college for their kids or pay the stack of bills on their kitchen table," he said. "And most of all, they are anxious and uncertain about the future -- about whether this generation of Americans will be able to pass on what's best about this country to our children and their children," he said. But despite all of this, despite the enormity of the task that lies ahead, Obama asserted: "I stand here today as hopeful as ever that the United States of America will endure, that it will prevail, that the dream of our founders will live on in our time." Obama said he is hopeful that things would change for the better. "And yet, as I stand here today, what gives me the greatest hope of all is not the stone and marble that surrounds us, but what fills the spaces in between. It is you, Americans of every race and region and station, who came here because you believe in what this country can be and because you want to help us get there," he said. "There is no doubt that our road will be long, that our climb will be steep, but never forget that the true character of our nation is revealed not during times of comfort and ease, but by the right we do when the moment is hard. I ask you to help me reveal that character once more, and, together, we can carry forward as one nation and one people the legacy of our forefathers that we celebrate today," he added.