I wish I knew my body better

For the last couple of weeks my training has been up and down. Running has been consistent in frequency, but less so in intensity. Lifting has been fairly consistent and better in intensity. Biking has been less consistent in frequency and intensity. For instance, yesterday morning I did the usual easy eight miles in the freezing cold after doing an intense nine-plus miles in Chicago two days before. Then I decided to hop on my bike rather than lift and I hammered for over an hour at close to 18 mph and felt great. I thought for sure that I would last like 20 minutes at 14 mph and bail. I wish I could figure out what triggers my body to feel good enough to run and then hop on my bike so I could replicate it on a daily basis. Maybe it's nutrition or sleep (although sleep is pretty consistent). Maybe it's the weather and as it gets warmer I will feel better. I don't know, I just wish I could figure it out soon.