Life drawing is a great break from science illustration. It's all about observation, you draw only what's right in front of you, nothing microscopic, nothing long gone in the past. You exercise the connection between your hand and your eyes. There's no background research involved, long discussion about content. There's a time limit, usually from 1 minute up to 50, so you've got to work fast and let go of agonizing over every line. It puts me in a sort of trance state and the time flies by. I've been trying to do more life drawing, both to improve my ability to draw people (lots of those in archaeological reconstructions), and also to keep up my observational skills. I'm currently taking a class at the Dundas Valley School of the Art. Today, besides the usual short gesture drawings, we worked on reduction drawings.
This technique consists of coating your paper with charcoal and then picking out the lighter tones with a kneaded eraser. You can then go back in with charcoal to adjust things a bit and add more darks. I really like this technique as it very forgiving, much more so than working with pure lines. You can go back and forth between adding and subtracting values forever (or until the model's foot goes to sleep). So I've had a lovely morning sketching. And now back to painstakingly cleaning up and laying out chipped stone illustrations for a Çatalhöyük publication.