Heidi Klum finds raising four children challenging.

The German supermodel - who raises four kids, Leni, seven, Henry, five, Johan, four, and 21-month-old Lou, with her husband Seal - explained that taking care of their brood is a juggling act.

She told US Weekly: "It's a huge responsibility to have four kids. They all have different likes and dislikes and activities that they want to do. You have to learn how to juggle all of that, and at the same time, give them each the love that they need.

"When you have one [child], you can focus on one. With four, you have to make sure [your attention] is all spread out just right. You have to understand how different they all are! And at the end of the day, there is not much time left for you!"

However, Heidi, 38, admits she is lucky that her children are a "united bunch" and says she and 48-year-old Seal are teaching them about responsibility by getting them to help take care of the family's two German Shepherds, Freddy and Max.

She added: "They always stick together and take care of each other. They love each other! They love helping Lou. They like to feed her [and] they include her in all their activities."

"The dogs are starting to teach them about responsibility and caring for someone else. They are also learning about rules, schedules with feeding and walking and sharing. Having the two dogs is big time sharing for the kids!"