I saw today’s exercise often on women’s workout plans and almost never on those for men. Maybe because it trains especially the external part of the thighs, which is seen as a problem area by a lot of women. Because it trains also the hip muscles and the lateral abdominals, I recommend it also for men.
I lay laterally on a mat supporting my torso on the elbow, holding the balance with the other hand. Then I start swinging the upper leg as high as possible upwards and then back down. Like the opening and closing of a scissor. After a few repetitions I turn on the other side and go on with the other leg.
Have a nice day!