If you've been doing a lot of computer work or even if you've been standing and doing a lot of things at counter height, it can make your shoulders get rounded forward and your mid back get rounded forward.
To make sure you have good flexibility (and it actually makes it easier for you to get good straight posture) sit in a chair, put your hands comfortably behind your neck, elbows just kind of forward comfortably, and then lean back over the chair.
I don't want you to cause any pain with this, but just the process of leaning backwards can help to get your spine moving and help to open up your chest and get everything more flexible so it's actually easier for you to stand up straight.
50% Complete