The cat dog exercise is one I find myself prescribing a lot for people (golfers and non-golfers). Generally a traditional cat dog movement to begin with (as shown in the video below), with progressions given as people improve.
The cat dog exercise can be a great exercise to help with mobility around the spine, pelvis and shoulder girdle (shoulders and shoulder blades). And it can be a great exercise to help with awareness of the spine.
Performing this exercise next to a mirror can help to identify if you are too much in one position compared to the other or if you find it easier to get into one position. It can give you a lot of information in this one exercise.
Improving your cat dog exercise can help improve your spine, shoulder girdle and pelvis posture for general life, but also can help transfer into a better golf set up posture too.
This is an exercise that can be performed everyday and even multiple times per day, or in a warm up before exercise. 1-2 sets of 10 reps can be a good place to start. Focus on what's happening and perform in a controlled manor.