Lookman was brought to Everton from Charlton Athletic during the January transfer window, and he has caught the eye with his performances.
The 19-year-old has already featured in five matches for Everton, and he has been handed two starts.
However, Koeman has been so impressed by Lookman’s performances in training, that he has not been shocked by the impact that the forward has made in the first-team.
“I’m not surprised because I am watching him in training every day,” he said.
“He now knows what intensity he is up against and the quality of the players around him.
“It’s a big challenge for Ademola but he is doing well. He is the future of the club. He’s a big, big talent who is working hard to improve, like everybody.
“Ademola is a good example in that if you are good enough you will play, and there are others here like him who will get their chance if they keep working hard.”
Lookman has already scored his first goal for Everton, after coming off the substitutes’ bench to score against Manchester City on debut.
Lookman is part of an exciting crop of youngsters currently breaking through at Everton, alongside the likes of Mason Holgate and Tom Davies.
Lookman is currently with the rest of Everton’s senior side training in Dubai, as Koeman puts the squad through their paces.
Everton are next in action in two weekends’ time, when they take on Sunderland at Goodison Park.