Figure drawing...

It happens that a pose of a model doesn't inspire me, in particular when I can't find any interest in shape or light. I also notice that I'm very sensible about the presence of the model, it has to be "whole"; even though the pose "could do", but I feel her or his mind is far away or the expression completely indifferent to the pose, it totally "cuts me off" and nothing good will come out of it.
I feel as if it's even destructive to draw then, so I try to find another subject that could do for a few minutes, like in this example above.