Who doesn't want strong, sculpted, shapely arms? If you're not seeing the results you're after from basic strength-training exercises, you've got to try yoga. These seven challenging poses require holding your own body weight in unique positions, so you end up working the muscles in your upper body more effectively. The burn you'll feel in your arms and upper back lets you know that you'll soon be loving your sexy, strong arms, just in time for strapless-dress season.