Judy Murray was on WomansHour this morning and mentioned Set4Sport/GetSetToPlay. The site has some simple games which can be played indoors or outdoors, to promote children's leg strength, balance, that sort of thing. For example Jumping The River (pdf) looks like an easy game to setup, need two ropes or ribbons or something to indicate river banks, then have something to jump onto as a rock when the river is wide (a hoop, bit of newspaper perhaps).
Thought this may be of interest to some of you, who if you are like me are not great at setting up PE activities so need little suggestions for things to do to help the children in our care develop their physical abilities.