London: Pop princess Britney Spears believes that the secret behind her toned figure is that she runs after her two sons.
The `Womanizer` hitmaker, who has five-year-old Sean Preston and Jayden James, four, with ex-husband Kevin Federline, claimed that running after them has made her more active in everyday life, a website reported.
"How do I keep slim? Having two boys definitely helps, and I love to dance. It`s the best way to stay in shape," Spears said.
Though the singer loves looking after her children she also likes to indulge herself in beauty treatments.
"I love treating myself to a spa day. Massages are my favourite," she said.
The 28-year-old singer enjoys changing her make-up style as well depending on her mood.
"Sometimes I keep it simple and don`t wear much make-up - just a little mascara and lipgloss. Other times, I`ll play around and do heavier make-up or some fun lipstick," she added.
However, when it comes to beauty icons, Spears blindly follows Madonna for ideas in revamping her appearance.
"I love, love, love Madonna! She`s one of my inspirations," she said.