Jennifer Aniston refuses to change her hair style because it makes her feel ''cosy''.

The 48-year-old actress believes she is a ''weird creature of habit'' and will ignore anyone's opinion about her appearance because she is comfortable with the way she looks and ''feels better'' having ''bronde'' coloured hair than any other style she has previously experimented with.

The 'Friends' star - who portrayed Rachel Green in the popular series for 10 years - told Vogue.com: ''Bronde?! That's what they're calling it? That's so funny. I'm a creature of habit. A weird creature of habit. I don't fix what's not broken and I don't care what people think and I don't care if people want me to change my hair. I like Californian blonde highlights. It's just cosy and it makes me feel better.

''And every time I tried other ones - that bob - I just go, Why did I do that?

''I don't know, I like what I like. It's sort of comforting - the consistence.''

The style icon has admitted her wavy locks are easier to manage when they are longer because they ''behave''.

She explained: ''I've got very wavy hair so it creates a challenge when styling but when its long, I can go wavy or natural or straight and it will sort of just behave.

Jennifer also boasts an enviably toned physique, which she has maintained by undergoing fitness classes and working out with a personal trainer.

Speaking about her fitness regime, she said: ''I go in and out of [certain exercises]. I do The Class by Taryn Toomey, and I'm back in the gym with my trainer, throwing heavy boulders around and pushing medicine balls and wiggling and shaking that big rope thing [battle ropes] ... They're hard! But it's fun.''

Although the American star finds battle ropes a challenge and will ''dip in and out'' of the exercise throughout the year, she enjoys it because it ''kicks [her] butt''.

She explained: ''I started doing that when I was filming 'We're the Millers' and I really liked it. It kicks your butt, though, so I dip in and out of that throughout the year. And then I do 45 mins of intervals on my elliptical. I raise the incline, run for two mins, walk for one, run for two ... and I do it for 20 minutes straight until I'm just drenched.''