Heidi Klum is revealing her secrets on how she keeps her marriage to Tom Kaulitz spicy. "I mean we were just lingerie shopping," the supermodel, 52, tells PEOPLE exclusively ahead of her much anticipated return to Project Runway1.

Heidi Klum and Tom Kaulitz’s sizzling chemistry is evident in every social media post, but their magical pairing almost didn’t happen. Klum, who is set to return to Project Runway on July 31, didn’t expect to marry for a third time after two marriages: Ric Pipino from 1997 to 2002,

Klum revealed the expected "secret" to keeping their marriage "spicy." The German supermodel was previously married to Ric Pipino and Seal. Heidi Klum and Tom Kaulitz look like they’re on a never-ending honeymoon,