This season is Lukaku's fourth in the Premier League and second with Everton, having joined the Merseyside club permanently from Chelsea in the off-season, but there has been a sense the Belgium international has yet to live up to his reputation with just six goals in 16 league games.
Having broken through as a professional in the 2009-10 season with Anderlecht - scoring 15 goals in 33 league matches - Lukaku has been well known in European football for six seasons but remains just 21.
"Sometimes I think people forget I'm still 21," Lukaku told The Mirror on Friday.
"They think I'm 25 or 26 because I've been around for a few seasons now.
"Sometimes, I look at Ross [Barkley] and think 'We're both young but people don't realise that'.
"I'm still 21, sometimes mistakes happen - things happen because you don't have the right experience. If I keep improving like this, then when I'm 25 or 26, that's when there will be no excuses."
Samuel Eto'o, 33, is a particular mentor for Lukaku.
"I'm picking up lots from him [Eto'o] and he has a tremendous football knowledge," the youngster said.
"He doesn't give me a yard. When I go to do finishing, he follows me across and says, 'It's you against me again'.
"He hates to lose and I hate to lose so when we are on the same team in the small-sided games, we never lose."
Lukaku says he also learns a lot from watching football - lots of football: "I watch a lot of games and in a week I can watch 10 games, easy.
"In Belgium, you grow up watching all the leagues - Germany, France, Spain, Italy, England - and I watch them all.
"I remember watching Bayern Munich v Man City last year and [Thomas] Muller was always running in behind, running in behind. He never got the ball four times. But the fifth time he did it - goal.
"I tried that in a game and the third time I did, I got it and scored."
