22K in 2:08 - 21K to go. Yes we can. Er, Yes I can

I hardly slept last night. That means I couldn't go out to run early. My legs weren't fresh as such since I didn't sleep and my left knee felt spindly.But I trust my quads to protect my knee.
Nonetheless, I set off at 10am and off I went. I warmed up then cranked up a little. The first 8K went like this: 6:02, 5:03, 5:15, 5:13, 5:14, 5:22, 5:27, 5:32 then the sun was literally baking me.That is 43:08 for the first 8k.
At any rate, I reckon that my target heart rate is 170-172.
The next 7 Kms returned 6:34, 7:07, 5:03, 6:05,5:07, 5:50, 4:58 which is 40:44
So at 15K I had done 83:53, which is, 1:23. Then it was simply so hot. It didn't make sense to continue being greedy. This week should be about distance, not speed.
At any rate, I plodded on and finished 22K in 2:08.
One major thing I learnt today is that this marathon business is not about your heart or lungs or mind: its all about your legs. If your legs aren't strong enough to ask for more oxygen, they wont get none and your heart rate will drop. So one must have fresh, fast legs.
I have 21K left to total 100K this week. No more speed for me until next week. Am tired as hell.
From next week, I taper for Stanchart.
Meanwhile, I digest what happened today.