"I didn't come into this thinking it’s going to be a fun thing that I'm going to do on the side. It's something I want to do my whole life. It's a career, so I needed to be really gentle with it. We had to pick and choose things very specifically."
Kendall also opened up about meeting Lagerfeld, who was responsible for the pictures used in her photo-spread in Bazaar.
"I’m really shy when I first meet someone—and to meet him was even worse. He would say something to me and I would just nod. It was like meeting a crush or something—I was mute," Kendall admitted. "He probably thought I was the biggest weirdo. And then every time we’d see each other, it would just get better and better. Now we’re totally BFFs."
Kendall added that Lagerfeld has helped her develop her skills as a model.
"He gives me some tips, little things, pointers," Kendall explained. "He makes me feel good when I’m working with him—we have good chemistry now."
Kendall also opened up on some more embarrassing topics, such as her love of buying shoes -- "I have a problem—I need to go to rehab for shoe addiction" -- and her past clothing choices -- "If I look back at episodes of my shows, I'm like 'Oh, God!' In one I'm wearing green denim pants, full neon green."
Kendall also showed some love for her big sister Kim Kardashian, saying that it's her style she admires most.
"[Kim] really knows how to work her style with her body. I think she could be a major fashion icon," Kendall revealed. "It’s so fun to be in Paris with her, but I’ll walk out and be like, 'Oh, my God, I love my outfit,' and then I’ll see Kim and I’ll be like, 'My outfit sucks compared to yours!'"
Kendall's interview appears in the May issue of Harper's Bazaar which hits newsstands April 21.