Kelly Clarkson's boyfriend has inspired her to get fit.

The original 'American Idol' winner - who recently revealed she was dating the son of her manager for five years, Brandon Blackstock - has admitted that her romance makes her want to look better.

She said about her tauter figure: ''I would love to say that it had something to do with my work, but it doesn't.

''I have a boyfriend, and if I'm being completely honest, no one likes to be not toned when you are dating someone.''

The 30-year-old - whose new singing competition 'Duets' premieres in the United States on Thursday (24.05.12), told reporters during a press conference that she has lost weight after increasing her workout routine and by restricting her diet.

She added: ''I'm eating better and working out, but I've always fluctuated within 20 lbs. My whole life I've been like that.''

Sharing a trainer with her talent manager partner, 35, offers more of an incentive she shared.

Kelly said: ''I tone whenever I want, and I chose to now because my boyfriend and I are both really into it. But we don't work out together.

''We did that once and I didn't like huffing and puffing. I didn't like looking all red and gross, so I don't do that.''

Instead the pair find other activities to do together.

She continued: ''We both love music so we go to shows together. I am just more active with him.''