besides the pull/injury while exercising - do you have other possible factors?
like what kind of job = desk or other static head/arm forward type postures, repetitive, reaching up/out/overhead??
previous whiplash or head/shoulder falls or sports injuries?
hyper mobile/ lax joints?

If you read thru our sticky threads above- start with post #1- those will help you to learn about TOS form many top TOS info sites & various therapy info sites also.