the thing is guys, i'm into sport, i know how to train and focus - diet is ok could be better. for some weird reason after 40 minutes i hit this brick wall and i quite literally run out of breath. then again it could be the heat, i trained in 35 degree heat in china today under the sun - bad idea. I will take your adivce ppl and gradually increase my session times, it scientifically makes sense - the more i increase training time the more my stamina will increase.
peace out
xx