[cbmcday]

Not the person you asked, and I have paid attention to this. I found "Run for Your Life" [1][2] to have useful insights and tips. The biggest one for me was starting with foot landing, where the outside of the foot near the little toe hits first, it spreads out nicely to start taking body weight. Then letting the rest of the outside of the foot land until the heel touches, and then somewhat relax the calf muscle and pull the heel back and slightly roll the ankle in, so the big toe is loaded for the push back and lift off. I play around with variations and sometimes, it becomes almost effortless, almost floating along, even on hard surface.

[1] https://runforyourlifebook.com

[2] https://www.youtube.com/watch?v=zSIDRHUWlVo