(Cover) - EN Showbiz - Heidi Klum has revealed the secret to her happy marriage with singer Seal.

The Project Runway host told OK! Magazine that couples should always try to keep the romance in their relationships alive.

Although the celebrity twosome have busy lives and are raising four children, Heidi says the key is to not let the fire extinguish.

"To try and always keep it that way," Heidi said of maintaining romantic relationships. "To not let the honeymoon stage ever have an end I guess. Keep it always exciting."

But the German supermodel says there is nothing extraordinary about her six-year marriage to Seal and they are a regular couple.

"I mean we're a normal couple too," Heidi shared. "We eat and exercise just like everybody else."

Heidi's other piece of relationship advice is that a woman should wear a gift from her partner even if she doesn't like it to "make him feel good".

The 38-year-old recently debuted her Wildlife jewellery collection that is inspired by elements of nature. (C) Cover Media