I'd resign... the government can't do all that much to fix the economy and I'd be overwhelmed.
If I had to stay on the job, I'd work on trying to promote innovation in our economy. I would encourage universities to work together with companies to try to discover new technologies that would allow our economy to move ahead. I would also set up a system to reduce health care costs by paying medical providers based not on how many procedures they'd do but on how healthy they kept their patients. This would help to reduce costs for American businesses and make them more competitive.