SANTA CLARA, Calif. -- There's no doubt, Jim Harbaugh loves this time of year.The colorful San Francisco 49ers' coach repeatedly referred to Thursday's start of training camp as a "rebirth." He said he is "relentlessly positive" and believes his team is up for the task of remaining one of the NFL's elite teams."They are cheerful and undefeated," Harbaugh said of his team. "This is the least the unhappy team I've ever been around.