I've been noticing these mental barriers when running and how unrelated they are to my actual physical ability.
I feel for me there are these hurdles at certain points near the start/middle of a run. Before the hurdle I feel I can't do it and don't have the energy or stamina. Afterwards, I find energy and an ease that I couldn't imagine having.
Today (w4r3) I noticed as soon as I start the first (3min) run, the very first second, I have the thoughts I can't do this, I'm tired already and I've only walked, my body feels too heavy for this. Then towards the end of the first run, it feels so natural and doable (of course it was still an effort).
Or for example I'll start a 5 min run, be ok at the start, seriously flag half way through (I'm always so shocked when she says I'm half way through that it hasn't been the whole 5 mins) but not long after I'll be in the flow of it with no doubt I'll make it to the end.
Anyone else notice these kinds of patterns before or during a run?