You may spend 20 minutes working your abs every other day, but you sit at a desk for hours upon upon hours a week. If you slouch at that desk, you are quite possibly undoing all your hard at the gym strengthening your abs and back. When you slouch, all your hard work slouches with you. Slumped over a keyboard, your abs essentially turn off and your back muscles get tired from being overstretched. Your core exercise should affect your everyday habits. Not only does this posture look bad, it feels bad too and can lead to all sorts of repetitive stress injures, like carpal tunnel, associated with desk jobs.