We all know models are genetically blessed—but you'd be a fool to think they don't sweat hard in the gym to tone and perfect their muscles. Kendall Jenner is no exception. On the model's eponymous app today, she spilled a few secrets for strengthening her abs.

"My abs are my favorite thing to work out. I love it when my trainer, Gunnar Peterson, kills my abs," she writes. "The next day, it hurts to even laugh. That's how I know I'm doing the exercises right!"

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If you're struggling to find time to dedicate to just your midsection (and you don't have a trainer on call), Jenner has a trick we could all try out. "Sometimes when I'm watching TV, I think to myself, 'I should be doing crunches and situps right now.' Then I get off the couch and do it," writes the model-mogul. And that's why she walked in the Victoria's Secret show—and I have rewatched Parks & Recreation three times over.

Jenner ends the post by recommending an Apple app called Instant Abs Trainer, which she says helps keep her motivated. The free app has hundreds of different strengthening exercises to choose from, whether you're in the gym or running around fashion week. Needless to say, we've already downloaded it.

From: Harper's BAZAAR US