hmmmm gotta agree with Oak and Emily on this one.

What Emily describes certainly is pain (and in any case suffering is just the state of enduring pain, physical or otherwise). Lactic acid, burning lungs - indeed can be awesomely physically painful, though not physically harmful.

The trick is learning what kinds of pain are safe to push through and which ones are telling you something is truly wrong. Pain is not always necessarily commensurate with injury.