As/if/when the spirit moves you - Idioms by The Free Dictionary
as/if/when the spirit moves you
if the spirit moves (one)
When one feels compelled to do something. Laura's grades are so bad because she only comes to class if the spirit moves her. I usually stay home on weekends, but I'll go out if the spirit moves me.
(do something) as/if/when the spirit ˈmoves you (do something) when you want to, rather than when you have to or are forced to: She works in the garden occasionally, when the spirit moves her.