One of the best ways to build lean muscle in your legs — the area of the body with the most potential for lean muscle — is by doing squats. And one of the best things about squats is that there are a few different styles, meaning you can switch your form up and prevent boredom from setting in too soon.
One option is to complete a basic squat: from a standing position, bend your knees and extend your arms outwards, helping you maintain your balance. Continue moving down until your butt is within about a foot of touching the ground, then stop for a couple seconds before reverting to your original position. Repeat 20 times. As you become better at the exercise, you can start to think about more challenging squats, like the jumping squat or frog squats.