He underwent surgery last month after rupturing an anterior cruciate ligament in his left leg while on holiday.
Muntari is set to remain on the sidelines for six months but the 27-year-old hopes to make a quick return to action.
“I cannot wait to come back, everything is going well and even psychologically I am feeling good,” he told Milan Channel.
“I have to be patient but everything is going well with the doctors.
“I do not think I will be out for too long, I will be back as soon as possible to help out my team-mates.
“We must win. I did not want to injure myself but these things happen in life and the injury is now a thing of the past.”