It seems hard to anchor my rib cage without contracting my abdominal muscles by basically sucking in my stomach. In the book, the woman appears to not have an inner corset while sitting and her stomach muscles 'appear' relaxed. Is it okay to constantly have my abs contracted while sitting? It seems to be very comfortable now that I've gotten the basics of sitting, as most of the tension is in my abs. Will my muscles eventually start to 'remember' this position naturally so that I won't have to contract so much?