It's always best knowing what you're walking into, good or bad. The good thing about The 21-Day Shred is that you're actually going to see some serious results. The bad thing about The 21-Day Shred is that you're going to be sore as hell and work your ass off... Sorry, but it's the truth. If you're up for the challenge, go ahead: DOWNLOAD The 21-Day Shred app for iOS to get the full training program, diet, and more. No iOS? No problem. Get a COPY of the PDF.

In the meantime, here's every ab exercise you'll do battle with.

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