Michelle Obama delivered opening remarks at the plenary session of the 2010 Winter U.S. Conference of Mayors on impact of childhood obesity around the U.S. She talked about the role mayors play in pursuing comprehensive solutions to improve children's health. She was followed by Energy Secretary Steven Chu, who spoke about the future of energy policy in the U.S. and energy block grant programs. He was followed by a special plenary session titled "Investing in Livable Cities to Meet 21st Century Transportation Challenges."