So how does the 49-year-old singer look so freaking amazing? Well, she puts in the work, that's for certain.

Let's start with her diet: Jennifer recently did a 10-day no-sugar, low-carb challenge with boyfriend Alex Rodriguez. (She convinced pal Hoda Kotb to do it , too!)

The challenge involved nixing starchy veggies, dairy, and fruits (which have naturally occurring sugars), while focusing primarily on non-starchy vegetables like cauliflower, zucchini, and broccoli, along with meats, nuts, seeds, and nut butters, along with various condiments and things like guacamole, olive oil, and salsa.

J.Lo finished up the challenge on January 30th, and almost immediately started talking about doing round two , so yeah, she's definitely hardcore when it comes to eating healthy.

View this post on Instagram Day 9 and feelin... like I cant wait for Day 10. Whos still with us? @arod #10DayChallenge #NoSugarNoCarbs @niyamasol #niyamasol #jloxniyamasol A post shared by Jennifer Lopez (@jlo) on Jan 29, 2019 at 2:23pm PST

Jennifer did a half-naked photo shoot for InStyle back in October, and told the magazine that she looks like she does, well, because she works hard for it. She's sworn off booze and caffeine, and she gets a lot of sleep. Ive taken care of myself, and now it shows, she says.

Jennifer also said she credits a new weight-training routine for keeping her fit, noting that she loses muscle when she focuses too much on dancing for fitness.

J.Lo and A-Rod also both swear by TruFusion workouts , which offers a variety of classes from yoga to boxing to bootcamp in rooms heated to 120 degrees. Alex Rodriguez, who's an investor in TruFusion, told People that "it's the best workout I've ever had in my entire life," for what it's worth.

In 2016, J.Lo also told Hollywood Life that she's a morning workout kind of girl. I work out three or four times a week. When Im in New York, I work out with David Kirsch-hes an amazing trainer," she told the magazine. "When Im in L.A., I work with Tracy Anderson. I like the balance that they both give me. They have two totally different approaches. I like switching it up with my body.

So yeah, let's just say that J.Lo's Grammys arms didn't just happen by accident.