We live in a society where bones are sexy.  The more we can see a person’s (or at least a woman’s) bones the better.  But sometimes when we can see bones it’s a sign we have weak muscles.
It’s the scapula (shoulder blade) that stands out to me the most.  Google search sexy scapula (because that’s totally normal) and these are the first two images you’ll get:

So what’s wrong with these two pictures?  Their bones are sticking out.  The scapula isn’t supposed to look like that.  It’s supposed to lie flat against your rib cage.  And if it doesn’t, it’s a sign of week muscles (specifically your serratus anterior, traps, and rhomboids).  When your scapula don’t lie flat on the ribs (called winging or an anterior tilt) you can have pain, discomfort and limited range of motion in your shoulder.  So we get to look sexy, sleek and thin, but we can’t move and we hurt. Pain is beauty, right?

No.  Instead you need to strengthen your serratus.  On a good note, the fourth picture of the sexy scapula Google search is this one:
Not only does this woman have a strong serratus anterior muscle (to be explained in a blog later this week), look deeper into the picture.  What is she doing?  That’s right…this woman with legitimate sexy scaps is doing Pilates. 
Proving (although perhaps not scientifically) that Pilates rocks!