Help please! I am quite happy with the way my 12 week diet plan is going, although I can't pretend it isn't hard at times. What I would like to do most of all is tighten up my tummy muscles so that it begins to look flatter instead of fatter! . I walk about 8 miles a day but please can someone advise on the most targeted and, most importantly, effective exercises that will help strengthen tummy muscles in particular. Thank you all very much in advance for whatever advice you can give.