I have virtually no ab strength. Tamilee's 15 minute "I Want Those Abs!" beginner work out just kicked my butt. Seriously, I've tried to avoid crunches since gym class in high school. All her talk of "long levers" and such now just has my tummy muscles groaning with what I'm sure will be even more soreness later.
But with all that I'm reading about strength training and the need to build your core strength and such, I think this is a workout I need to keep coming back to. I'm watching the intermediate level one now, and it's gonna be some time before I'm ready for that!