Renee Zellweger can let go of her problems when she's out running.

The 'Judy' actress find it incredibly relaxing to pull on her trainers and ''get out on the road'' because she can ''process'' anything that's bothering her and leave her concerns behind.

She said: ''I run a lot. I saw this fantastic ad once where the girl's running along the road and all these words - 'stress', 'fatigue', 'anxieties', 'illness', whatever - are flying off her in the wake of the wind.

''I thought, 'Well that's the best representation of running that I've ever seen.'

''Because that is exactly my experience when I'm out on the road - I process whatever it is that might be bothering me and off it goes. I leave it behind.''

The 50-year-old actress admitted she was ''naïve'' about how much fame would affect her life and she was thankful for a warning she received from director Mike Nichols while she was working on 'Jerry Maguire'.

Recalling how he asked her if she knew how fame would change things, she added to Britain's HELLO! magazine: ''I naively said, 'Yeah I guess so.' And he said, 'Well, there's nothing in this life that can prepare you for he changes you are about to experience.'

''He said, 'Fame is tricky. Think of it a little bit like Medusa. It's insidious. It never goes away.

''Wherever you go from now on, it's always right around the corner and if you look directly at it, I promise you that just like Medusa, it will turn you to stone.

''But on the other hand, you've got to keep an eye on it - because if you don't, it's doubly dangerous because you won't know where it is.

''So look at it, but do so indirectly, through your family and your friends.

''At the time, I didn't quite understand what he meant.

''But obviously, when I think about it now so many decades later, it really resonates with me because he was right.

''It was the best advice I could have had in terms of staying healthy in a life that requires you to navigate that unusual path that is dictated by fame.''