Bridges are effective in strengthening and toning your butt, hips and thighs. To do a basic bridge, you need to lie on your back, place your arms by your side and bend your knees with your feet placed firmly on the ground. Then lift your but up, until your body comes into a straight line from the shoulder to the knees. While you lift your butt up, squeeze it for two seconds and let go as you bring it back to the ground. Do a set of 3, each consisting of 15 reps.