This shorts season, why not show off your thighs? The best upper-leg-sculpting secret I know is Chair Pose. By squeezing your legs together and then lowering your hips to almost knee level, you can quickly strengthen and firm your thighs, front and back. Do this quick pose at least 4 times a week (every day is even better), and you should see results in about 3 weeks.
Stand with feet together and hands on hips. Begin to bend your knees as if sitting in a chair, moving your hips back; your torso will tilt slightly forward. Keep bending your knees until your thighs are parallel to the floor (or as close as you can get). Stabilize your back by drawing your belly in and tailbone down; relax your shoulders.
If comfortable, increase the challenge by raising your arms until they are in line with your ears, keeping your shoulders relaxed and jaw soft. Hold for 5–15 breaths, then return to standing. Repeat up to 3 times.