Read a bit about "overtraining" - You may not be there yet, but you should be aware of it.

http://en.wikipedia.org/wiki/Overtraining

"Overtraining is a physical, behavioral, and emotional condition that occurs when the volume and intensity of an individual's exercise exceeds their recovery capacity. They cease making progress, and can even begin to lose strength and fitness. Overtraining is a common problem in weight training, but it can also be experienced by runners and other athletes."

"Physiology Improvements in strength and fitness occur only after the rest period following hard training (see supercompensation). This process can take days to complete, depending on the intensity and duration of exercise leading to the overtrained state. If sufficient rest is not available, then complete regeneration cannot occur. "