I'm not a bad road and trail runner, but put me on the fells and I suffer! 😂 It's not so much the hills - I include a decent amount of vertical in all of my running - but rough ground: even on the flat, heather and tussocks just kill my legs in no time at all.

Running isn't rocket science, and an/the obvious answer is "run on rough ground more, idiot". That aside, does anyone have any training/technique advice?