Lewis, who had elbow surgery in July, said Friday that he's doing forearm exercises and hasn't felt any residual soreness.
"I'll start throwing in January, when I would normally do it," Lewis said. "We set expectations at the All-Star break, but those are very cautious. It's all based on how I feel. If I feel good before that, I'll pitch. We'll take each step based on how I feel."
Lewis signed a one-year, $2 million contract (plus up to $4 million in incentives) for the 2013 season in the hopes of showing he can get healthy and return to form and then, hopefully, get a multiyear deal.
The 33-year-old was 6-6 with a 3.43 ERA in 16 starts before having surgery July 27 to repair a torn flexor tendon. He was signed by Texas before the 2010 season after performing well in Japan.
Lewis was the Rangers' top postseason pitcher in 2010 and '11 as the club won the American League pennant in both years. He was 4-1 with a 2.34 ERA in eight playoff starts, including a 1-0 mark and a 2.29 ERA in three World Series appearances.
"I feel great," said Lewis, who is doing his work at his home in Bakersfield, Calif. "I don't feel any pain and I have my range of motion. I'm not going to do anything to put my career in jeopardy, but I'm doing my exercises and getting ready."