Shields, who underwent patellar surgery on June 16, and spent the final 117 days of the 2009 season on the disabled list, met with team trainers last month and was instructed to proceed with caution in terms of throwing off the mound.
Shields, who turns 35 on July 22, is embarking on the final year of his three-year contract.
Blessed with a remarkably durable arm and an intense desire to compete, he is a Type A-plus personality, something the Angels' medical and training staffs always take into consideration. He'd take the ball and work 162 games if manager Mike Scioscia let him.
Shields' spirits were raised by a visit to Angel Stadium four weeks ago. He threw off flat ground with several teammates and experienced no pain in the knee, providing optimism that he'll be in his customary late-inning role on April 5, when the Angels welcome the Twins to open the season.
"I played catch there for two weeks," Shields said. "I was very encouraged when I was out there throwing. I got all the strength back playing catch."
Starters Jered Weaver and Ervin Santana were there, along with bullpen catcher Steve Soliz.
They discussed how deep and talented the bullpen figures to be with hard-throwing Fernando Rodney, signed as a free agent, and Brian Stokes, acquired from the Mets, joining Brian Fuentes, Shields, Kevin Jepsen, Jason Bulger and Matt Palmer.
"We were talking about that," Shields said. "Our starters can go a lot deeper, but if they get us to the sixth inning, we should be in good shape with all the arms we have down there.
"I'm really excited about this season."
Shields, the Majors' most durable reliever with a total of 425 innings from 2004 through 2008, appeared in only 17 2/3 innings with a bloated 6.62 ERA before finally caving in to the pain and going on the DL on May 27. Despite favoring his landing knee, he still managed to hold hitters to a .239 batting average, slightly up from .226 lifetime.
His career ERA coming into the season was 2.93 in 428 games, 14 as a starter.
Shields, taken in the 38th round of the 1997 First-Year Player Draft, led the American League in holds in 2006, 2007 and 2008 setting up for Francisco Rodriguez. He preserved leads 31 times in each of those seasons, a model of consistency with his darting fastball and big curveball.
Angels pitchers and catchers are set to report to Tempe, Ariz., on Feb. 17, and Shields will be there.
"I'm really looking forward to getting back on the mound and competing," he said.