Britney Spears can't motivate herself to exercise. The 'Womanizer' singer - who has two sons, Sean Preston, three, and two-year-old Jayden James with ex-husband Kevin Federline - insists she is nowhere near as fit as she used to be because she has lost the desire to visit the gym.

She said: "I used to be a workout freak but after I had my kids it was a lot harder to get back into that routine. "I used to love going to the gym but as you get older and have more responsibilities, you lose that kind of discipline. Even now I have a much harder time getting mentally psyched to train.

But once I'm in the gym I start getting into it and I feel great." Despite her hatred of exercise, Britney says she is taking more care of herself by ensuring she gets enough sleep. She added: "I like going to bed early and getting up early. I think it's a much better way to live my life, especially when I have the kids - I need to have a lot of energy because they have so much energy themselves.

"I'm just not that into going out late at night or going out to clubs any more. It's the last thing I want to do."