Exactly! I don't understand how his heart rate is below 100 when running 10 kilometers (he says).

Try working on your briething. I've never run very far let alone a marathon(though I have played football non-stop for several hours many times when I was younger)... but 've found that by taking deep breathes while I run/jog means I can go for longer and without discumfort(until I stop) as opposed to when almost panting like a dog, it's as-if it has physchological effect and my body just refuses to work.