Crappy workouts

Just came in from a majorly shortened bike ride because it sucked. My heart rate zoomed up, I was out of breath, sweating like a hog and I was just miserable so I cut it short. This ride was not any faster than I have been riding. I just felt like crap. Yesterday, my run sucked too. Again, not any faster than normal. I do not know if I am getting a cold or something, or my iron is down or I am just tired. Whatever it is...it really annoys me. What to do...I am supposed to run 10 miles today...I hope I can do it in 2 different sessions and feel better than I have today and yesterday. This is really frustrating...add to that I feel like I just keep repeating the same day over and over and over again. Got to get back into the swing of things. I hope starting the P90x this week will help.