It’s a tough one
I’ll have my clients lie on their backs, knees bent and learn how to do a pelvic tuck while feeling their abdominal connection
I will also ask them to contract and feel the contraction
I also bring in pictures of the muscles/bone/attachments or we google them.
I talk about posture and the integration of back muscle along with the abdominals.
I use a mirror and show them
It’s not easy!
Once they become stronger they will start using thier abdominals much more.