You don’t need to lift hundreds of pounds to work your thighs. In fact this 21-day thigh workout challenge is completely bodyweight based. You need no equipment except a mat and yourself.  You can do this challenge on its own, or stack it on top of your regular workout. The four moves you’ll be doing are great for the inner thighs, quads, and hamstrings.  Each day, do the number of reps assigned for each exercise, resting 30 seconds between exercises.