Heidi Klum and Seal keep the passion in their marriage alive by having "date nights."

The former Victoria's Secret model - who has two sons Henry and Johan with the British singer and a daughter Leni from her relationship with Formula One team boss Flavio Briatore - thinks the secret to a happy marriage is making time for each other.

She said: "Seal is my best friend, my lover, my husband and the father of our children. We have a settled life. We have fun together. We travel the world and go on holidays - and we have date nights!"

"We go to a restaurant or to the cinema. We also spend some holidays alone - there are moments that are reserved just for the two of us."

Heidi also revealed Seal can make her smile any time he wants by telling her what he thought when they first met.

She explained: "He tells me that he thought I was a beautiful princess and that any man in my life must be the happiest man ever. And he has become that man."