To improve my grasp of human anatomy, I'm doing one sketch from a photo reference every day.

Same rules as before:
It has to be done in less than 1 hour, I can only use the one brush (Though I can choose which brush before I start), and I can only use black. No undo, no erase.

I'm not concentrating so much on re-producing the whole picture this time around though, more just trying to get correct looking human body shapes.

This one is from a diagram in an anatomy textbook rather than a photo of a naked lady.