George Clooney says it's ''not much fun'' to age on screen.

The 58-year-old actor first found fame when he starred as Dr. Doug Ross on medical drama 'ER' from 1994 to 1999, and has since made a name for himself as a Hollywood A-Lister, with his latest project seeing him star as ''grumpy old man'' Scheisskopf in a TV adaptation of Joseph Heller's 1961 novel 'Catch-22'.

And George says that whilst he enjoyed playing the older character in the Channel 4 show, he isn't a fan of being able to watch himself get older through his various projects.

Speaking to The Sun, he said: ''It's not that much fun to age on screen! But I enjoyed playing the grumpy old man on this. If you're going to take 18 months out of your life (working on a project), it has to be worth it.

''There wasn't a lot of subtlety to what I did. I just got a lot of yelling out so I could come home and be nice to everybody.''

Although George isn't a fan of ageing on screen, he isn't considering a career change at all as he recently said he has no ''interest'' in going into politics.

The 'Money Monster' star - who has two-year-old twins Ella and Alexander with his wife Amal Clooney - said: ''I am not going to get into politics. It doesn't seem like a very logical place for me to be able to apply what skills I have. I don't have to make compromise for the things that I stand for and the things I believe in, like politicians do. So it is not something that interests me.''

George is dismayed with the state of politics around the world right now and the slide ''towards authoritarianism'', but he remains ''optimistic'' that everything will work out for the best in the next couple of years.

He added: ''It is a very nervous time around the world. People sliding towards authoritarianism, it is something that is nerve-wrecking and that we should constantly monitor. The press do a very good job with that. I happen to be an optimist and I think that things turn around and it will hopefully head that way in the next election cycle.''