Illustration: Davidy Wyffels

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Lunge Matrix

What it works: Hip flexibility, glutes

Leads to better sex because: The larger the range of motion in your hips, the more easily you can get into and hold any position you and your partner think of, especially ones where you're putting your legs up high or reaching down low, says Sari Locker, PhD, a sexuality educator at Columbia University. Having strong glutes helps you generate power if you're the more active partner in any position.

How to do it: Picture yourself standing in the middle of a clock, with 12 o'clock on the floor in front of you and 6 o'clock directly behind you, says Susan Stanley, an Equinox trainer. Step forward with your right foot into a lunge position, with your foot at 12 o'clock. Keep your weight in your right heel, and push off of it to return to starting position. Do the same thing with your right foot at 1, 2, 3, 4, 5 and 6 o'clock, then switch to your left foot and lunge at 6, 7, 8, 9, 10, 11 and 12 o'clock. Once you feel comfortable with just your body weight, you can add dumbbells to increase the resistance and build more strength. For a more advanced challenge, you can increase your speed (while keeping the correct form) to add a cardio boost and improve your stamina for those long sessions.