This is a problem I've been having for years, but just recently (like within the last year and a half) I've become very aware of it and how it is impairing my riding.
My left shoulder almost constantly falls forward. I believe this is because I play the flute, and have been for almost 10 years now. Because of the position of my body while playing, it has become a habit for my left shoulder to always be dropped forward. Not enough that I'm slouching or even enough to be noticeable, but it's there.
It's not as noticeable while I ride to the right, but when I go to the left it's a constant struggle to keep it up.
I wanted to know if there are any exercises I could do to help prevent this, or at least make it easier to deal with. Unless I am constantly reminding myself to put my shoulder back it will always drop forward while I ride. It is just so frustrating because I know if this wasn't happening it would help my and Navigator's balance and bend and everything.