If you sit down all day, (much like I'm doing right now, and no, the irony is not lost upon me), you need to get some exercise work into the back half of the body to manage this. Once your posture starts to go, the whole ship can get off course.
Since everything we physically do is powered by how well our muscles move our bones, you might want to give this some attention on a regular basis. One of the better ways is to train the mid and upper back muscles. In a perfect world, you'd turn this into a total body movement to involve the glutes and core.
When we move, our muscles and bones integrate (see what I did there?) together to produce movement. Much like the foundation of any good relationship, the better they can communicate, the better you'll be able to move.
The sequence in the video below is an "enjoyable" super set using a Stick Mobility and suspension trainer combo to hit the back half of the body feet to fingers. The first part will really challenge the core and glutes to hold the whole operation together so the shoulder blades can do their thing to move back and forth.
Once you get to the second part of the sequence, your muscles should be pretty primed. Same movements, different force applications, but a whole lot of fun when they are combined back to back.
While this is a great combo, you have to ABSOLUTELY own your rib cage to be able to do them both successfully (READ: you should experience ZERO low back discomfort doing this). If you don't feel the abs and glutes immediately lock down as soon as you start to move, stop and change the angle to lighten the amount of force used. If that doesn't work, stop the exercise and choose an alternative that you've had success with training the back half of your body in the past.