I fix the backs of sedentary people and of several elite athletes, also middle range  Crossfit athletes.
One thing Ive notice about those with bad backs is their ability to push themselves beyond the call of duty.  In fact they have the reputation of being hard workers, motivated and always on the go!
The reality is , once the doors are closed, they  can head for the settee and slump. For hours!!!! They can happily stay in bed if allowed, and they can be very , very lazy.
Hard ( some would say obsessive) work can sometimes be matched by back destroying  activity elsewhere.