The Spaniard tore the anterior cruciate ligament in his left knee during Bayern's 2-0 defeat to Borussia Dortmund in the DFL Supercup back in August.
Martinez underwent an operation in Colorado a week later and was subsequently ruled out for several months.
The 28-year-old former Athletic Bilbao man is pleased with the progress he is making with his recovery four months after suffering the injury.
He told Bayern's official website: "We're right on track.
"I'm feeling better every day. I'm managing more and more exercise, and that's good for me mentally.
"My leg has to become healthy, and my head has to stay healthy."
Martinez also spoke of the difficulty he had in facing up to the extent of his injury following his operation in the United States.
He added: "That was the most difficult time. You can't walk, and you basically can't do anything. Friends, team-mates and the physios kept geeing me up and wishing me all the best.
"It helped me. But I was really down at times and avoided contact with the team. It wasn't an easy period."