Tracy Anderson says Gwyneth Paltrow is her ''best student''.

The celebrity trainer has praised her best pal and business partner for her commitment to her healthy living lifestyle and fitness regime, and finds it upsetting that people want to criticise the A-list actress for being an overachiever.

Tracy exclusively told BANG Showbiz: ''Gwyneth Paltrow is my most acclaimed student. The thing about Gwyneth is she's an extremophile. How can she go to all these extremes of being a successful actress, being a wonderful mother, being a lifestyle expert, being a partner to me in fitness? And looking better in her body than she did at 20?

''When people see someone in that position they envy that or make excuses for why they can do it. But the thing is with Gwyneth that sets her apart is that she has a growth mindset. Gwyneth loves to learn. She executes things and sees them through to actually have the results.

''She's remarkable that way. She's speaks multiple languages, she has learnt to play the guitar for roles. She does things right. I think it's unfortunate that when people see people in successful positions they think they got given that, or they got lucky. A lot of the time that's the case. I know that's not the case with Gwyneth. She works very hard, she's an achiever.''

The entrepreneur - whose A-list clients include Jennifer Lopez, Kim Kardashian and Madonna - has teamed up with Xbox Fitness to give people a chance to get a body like Gwyneth from the comfort of their own home, with Tracy insisting all it takes is dedication and hard work.

She added: ''Gwyneth wants to learn, she's disciplined and she doesn't have a big ego. She knows if she want the results, she has to do it. For seven years, six days a week, that girl has done her workout!''

Xbox Fitness is a new online service that takes the world's best fitness videos and makes them interactive with the power of Xbox One, personalizing your workout with instant feedback, smart recommendations and social challenges. It features an extensive library of videos from the world's biggest fitness brands, including Jillian Michaels, Tracy Anderson and Insanity.