Jonah Hill thinks actors taken ''seriously'' if they are in good shape.

The 28-year-old actor has been working out to get fitter for his forthcoming movie roles because he believes it is a ''sign of maturity'' if people are healthy, and he isn't happy that he most praise he has ever received came when he was ''big'' in 2011 sports drama 'Moneyball'.

He said: ''I think there are a lot of talented dramatic actors who are all different shapes and sizes. I think as I mature in many different ways - physically, emotionally, literally grow older - I think different roles are afforded to me and I think as my resume matures... I was big in 'Moneyball' and that's the most praise I got for a performance. I don't think like that.

''I think it is about the work you are doing. Getting in better shape is a sign of maturity. I think you are taken seriously.

''I think Bennett Miller said that about me, 'That I could tell he wanted to shed his skin and get out of whatever box he is in.' I didn't think about that at the time but when he said that I was like... Oh! A very insightful guy.''

Jonah recently starred as babysitter Noah Griffith in 'The Sitter', and he enjoys working with children because he believes they do not get ''jaded'' unlike his generation of acting talent.

She added: ''They're great. I have got nephews. The spontaneity and the energy. My favourite thing is that kids are not jaded. They are not over it. Everyone in my generation is over everything. Everything, 'I'm over this'. That's what my generation is like, 'Whatever. I'm over it.' Kids aren't like that. Things are exciting to them. That's infectious to be around.''

'The Sitter: Totally Irresponsible Edition' is out on DVD and Blu-ray now.