To stay motivated, take your measurements and weigh yourself. Write those numbers on a piece of paper and put it away for six weeks. Write your goals on another piece of paper, and put that where you'll see it every day. Never feel guilty about not staying on track. Pick yourself up and move on.
Persistence is the key to success.
I've read that a good way to maintain a firm stomach is through respiration exercises while doing chores or simply standing around. The process of breathing does use muscles along the rib cage and abdomen, but I'm not aware of breathing exercises that strengthen those muscles. Check a library for books or videos about yoga, which emphasizes controlled breathing. More work equals better results. You can work the abdominals every day.