The Carters took a break from their annual winter retreat fundraiser for the Carter Center for a ride on what's called a Trikke. The couple invited the president of Trikke -- as California-based company -- down to San Diego to ride with them."When the president asks you to go for a ride, a Trikke ride, wouldn't you say yes?" said Trikke President John Simpson.The Carters are in San Diego for a five-day winter retreat benefiting the Carter Center, their nonprofit organization that fights healthcare problems around the world."And we have a very strong democracy program where we've dealt with 89 elections around the world," said John Hardman, president of the Carter Center.This is the first year the retreat was held in San Diego. It raises hundreds of thousands of dollars for the Carter Center.However, it is not the first time the Carters have been to San Diego. A young Carter couple lived in San Diego during the Korean War, when Jimmy Carter was stationed on a Navy submarine."We lived in the most ghetto area of San Diego at the time and luckily when they put the bridge over to Coronado, they cleared out all the area where we used to live," said Jimmy Carter. "But we love San Diego. It's one of the nicest cities now in the world."The retreat wraps up Sunday.