How important is motivation in determining the virtue/non-virtue of a karmic action?

I ask this question because I assumed the importance of motivation being paramount in determining the virtue/non-virtue of karmic action was widely shared among all traditions. Anyway, I'd like to know if this assumption is correct from practitioners of other traditions. So how important is motivation in determining whether a particular action is virtuous or non-virtuous? Are there any actions where motivation is not important? Are there any actions where it is the only thing that is important? Something in between?