3. You’re sucking in your gut. 

While you may think you’re giving your abs a workout by sucking in, activebeat.com says you’re actually doing more harm than good. When you suck in your tummy, you’re putting the same pressure on your ribs and diaphragm as when you’re hunched over. This forces short, shallow breathing, and doesn’t allow you to release the necessary carbon dioxide from your lungs.

RELATED: Treatment may be able to prevent the progressive accumulation of scar tissue (fibrosis) in newly transplanted lungs that eventually cause those organs to fail, researchers report.