"I feel like I grew up too fast a long time ago," she says. "Having older siblings, you grow up around adults, so you mature more quickly. I saw my sisters and parents working every day, so I was pretty much brought up to be a workaholic."
Kendall confesses that she's a little uneasy about leaving her teenage years behind. "But I just turned 19 a couple weeks ago, and I'm scared to be 20," she tells WSJ. "It's the first step out of being a teenager."
Big sis Khloe Kardashian is doing her part to ease Kendall's anxiety, offering up some sage advice. "My sister Khloe always says to me and my younger sister, Kylie: 'You have your whole life to be an adult but only so long to be a kid.' And we get it," she says. "In the right situations, I try to be as immature as I can sometimes -- react to things as if I were 12. You can’t take things too seriously."