As I've said before, training, be it for CrossFit or using CrossFit as a tool for your sport or activity, is all about balance. It's a balance between stress and recovery. Stressors include the activity itself, but also, life stressors, such as work, keeping track of kids, balancing a checkbook, or anything that has the potential to raise your heartrate and/or blood pressure. Recovery is exactly what it sounds like, and it includes nutrition, hydration, and rest, both sleeping and simply kicking your feet up on the couch for the evening.
Many folks have a problem discerning when they are overtrained, also know as over-reaching. Dutch Lowy, CrossFit coach extraordinaire, has a great blog post about overtraining. While I don't visit his blog daily, it's on my weekly list, as he has some good insight in to both coaching and being an athlete. Read the article and tell us what you think. The comments made to his post add to the mix, and are worth reading too.