Twins first first baseman Justin Morneau joined his teammates for the first full-squad workout of spring training Friday. That could be viewed as encouraging. But Morneau provided reasons for concern.

In a 15-minute interview before taking the field, Morneau said he's worried about his career ending if he continues to have concussion symptoms that have plagued him since the middle of the 2010 season after he took a knee to his head as he slid into second base in Toronto.

"I don't think there will be a career if it's something I'm dealing with,'' he said. "That's the reality of the whole thing. I'm obviously not going to continue to mess around with this if it continues to be a problem. There comes a point where you can only torture yourself for so long. It's something I love to do, but you keep preparing and you keep being left out, that's something that nobody wants to go through.

"Obviously it's been a tough winter that way. I try not to think about that kind of stuff. Obviously it's crossed my mind and it's something I've had to think about, but when that stuff comes into my mind I continue to look for something positive, and look how far I've come in the last week or in the last month and just hope it continues to go well.''

Morneau went through fielding drills and took batting practice. He sprayed line drives around Hammond Stadium against coaches' pitching. When a Twins pitcher took the mound, Morneau didn't swing at a single offering, opting to track the ball out of the pitcher's hand to the catcher, which hitters do sometimes.