Working the Backside: Glute Max
A toned glute max gives a once flat booty serious curves. Generally considered the largest muscle of the body, think of the metabolic power you can generate by building and toning the glute max. The traditional squat is often considered the gold standard for working this muscle, but after researching the matter, the American Council of Exercise found a handful of exercises that can squarely compete with squats, including bent knee donkey kicks and lunges.
The bent knee donkey kick is perfect for isolating the glute max; you can hone in on the muscle during this exercise even if the motion is small. Here's a a video explaining this simple exercise. Working the glutes while standing with lunges prepares the muscle to work for you when walking and running, adding a functional component to your work. But if your knees bother you, stick with the donkey kicks.