Despite winning seven world drivers' championships before returning from retirement last season, the 42-year-old has not reached the dizzy heights of his previous successes on the track.
He has been forced to retire from races twice this season and his best finish was sixth at the Spanish Grand Prix on May 22.
But the German insists better things are to come and hinted he would be willing to extend his contract with Mercedes, which expires next year.
"It took me five years at Ferrari before I won my first title and Red Bull has taken five years to get success, so why should we manage it in just over a year and a half?" he told reporters before Sunday's Canadian Grand Prix. "We are not magicians."
Schumacher is currently 11th in the world drivers' championship with compatriot Sebastian Vettel of Red Bull dominating the season so far with five wins from six.
In the constructors' championship, Mercedes are fifth with 40 points, but Schumacher believes brighter days are ahead.
"We are in the process of creating something great," he said. "And that's just not going to happen overnight. It will take a while until we will get to the front. But we will do it."
Since he ended his three-year hiatus, Schumacher has scored a total of 86 points for Mercedes, never qualified better than fifth and not been on the podium. He has been fourth three times.