A couple of days ago I injured one of my costochrondal joints doing a clean (first rep of first set of the day). Apparently I didn't warm up enough and had poor form. I was also trying out a new kettlebell (10# heavier).
Shortly after our workout and for the rest of the day, I could hardly breathe without pain. After some reading about it, I was convinced it was going to take several months or up to a year for me to heal.
Today, I did my workout as scheduled. I feel mostly fine, amazed at my body's ability to heal itself.
I learned some important lessons about form, warming up, going heavy, and getting old.