I believe it was the famous Tour de France cyclist Tyler Hamilton who said something like, “I’m good at pain. I know when I’m at my limit when I get the faint taste of blood in my mouth.”
It’s his phrase, “I’m good at pain” which lingers with me.
As an athlete, I've learned to accept a certain amount of pain -- that burning feeling in your body that screams at your brain, "stop"! But I've noticed that over the years that I've gotten better at dealing with pain (not speaking of injury, here). In these painful efforts sometimes I'm able to even even work harder! Here's the reflection: pain can be a powerful prerequesite for achieving greater fitness. Like someone said, "pain is weakness leaving the body."
So get out there and embrace a little suck today!
Greater fitness awaits if you do.