Everything happened so naturally without myself realizing it, maybe it was to avoid the injury that keep coming back after each mid to long distance race.
There is physic behind it, not simply anything plucked from the air. Watch the video and hopefully it will help you. You don't have to be a barefoot runner immediately, because our legs are pampered for quite some time already, try the forefoot strike, change to minimalist shoes, etc.
Take progressive steps. Good luck!