CrossFit is one of the most humbling sports I have ever encountered. (Is CrossFit a sport? That's for another post.) I have played football, baseball, basketball. I have ice skated, climbed walls, ran 5Ks. Nothing slapped me in the mouth like a WOD (Workout Of the Day) at the local crossfit box.
To summarize, crossfit is the ultimate gut check and you MUST check your ego at the door. Take a break when you're hurt and don't rush back. Remember, the reason we work out is so we can enjoy our life. You want to be able to push yourself slowly and get better with each workout, not worse. You don't want to be hobbling around the office like me, do you?