If you are serious about your dancing then when you dance tighten those muscles in your buttocks and draw your naval to your spine. You don't have to have muscles like an Olympic sprinter but make the most of what you have. Try a Change Step in the Waltz with them relaxes and then tight. Which one is the more controlled and balanced. Rumba walks are the same. You should not be able to get an ATM card between the buttocks.