When Justin Timberlake was designing his William Rast biker-inspired fall collection, he had one inspiration and one celebrity in mind: his girlfriend Jessica Biel!

Justin said: "I always have one celebrity on my mind. I think it's pretty obvious, isn't it?" Justin's mom, Lynn Harless, also had some nice things to say about JT's woman.

Lynn said: "Just look at her! How can you not be inspired? She just climbed Mt. Kilimanjaro! At Christmas time, I heard this sound in my gym and saw Jessica. She was on the treadmill running as fast as she could go with a 40-pound backpack. I was like, 'Okay, she's amazing!'"