Low point?

Today I didn't feel quite well right after I ran 400m, I was feeling tired and puffing well before my normal endurance level.

Maybe I didn't eat anything before I goto gym, or maybe it's just that I am at the low point of 'physical cycle'.

ended up ran 2k, walked over 1k, burnt 200cal.

Then did the back muscle and triceps, Back was OK, I was able to push myself to do three sets of ten, but I could not focus when doing the triceps.

Again, something not right.