From Robbie McEwan on twitter:

suffering=>fitness

This joins "pain is a sign of weakness leaving the body" and "pain is temporary, quitting lasts forever." Also, "pain heals, chicks dig scars, glory lasts forever." Even though I'm not trying to impress any chicks with my scars.

And of course there's "harden the f*** up." I need one of those wristbands.