Paul Rudd has been having a ''slow and steady'' mid-life crisis since he was 24.

The 'Knocked Up' star didn't experience any feelings of panic about his loss of youth when he turned 40 in 2009 because he'd accepted he wasn't young anymore in his 20s.

He said: ''It wasn't a big freak-out, mid-life crisis moment for me. I feel like I've been having a slow and steady mid-life crisis that kicked in around 24 and it's just been a gradual thing.

''But events in my life that happened before I turned 40 - like having a parent die - were the shift for me. Those made me feel, 'Oh, I'm not a kid any more because I've experienced that.'

''When I was 20, I was like, 'When I'm 40, I'm going to own a house, I'm going to be really set in my career.' ''

Despite turning 43 last year, Paul insists he never takes himself or anything to do with his acting career too seriously.

The comic actor - who stars in 'This Is 40' about how a couple deal with entering their fifth decade - told Nuts magazine: ''Whatever you do, you can't take life seriously. We can't take ourselves seriously, that's what I mean.''