The former Derby County attacker has been sidelined since November 6 with a calf injury and in total has missed six league games so far this term.
He has not played for Scotland since March but says he is only setting his sights on fitting back into Neil Lennon's plans as the second-placed Hoops continue to chase Old Firm rivals Rangers.
"I have spoken with Craig and he's not going to hand out call-ups and caps just for the sake of it.
"While I have been injured I've not been involved in many games over the last four weeks so it's just important for me to stay fit, keep getting fitter and hopefully, if I start producing the football I did last year, I can force my way back into the squad.
"But that's the last thing on my mind at the minute, I just want to get back into the Celtic starting XI and produce the football I'm capable of."