"Active Drawing" is a term that I made up.
Basically it means drawing what you see from a photo on your computer screen. While it is not as ideal as drawing from a live model, you still gain the benefit of practice translating what you are seeing.
These days, there are numerous sites that sell model poses from 360 degrees around - and you can download them directly to your computer. The photography is pretty good, and projected on a good sized monitor next to your easel, you can do some descent drawing and get good practice even if you cannot get yourself to an actual live model.
One site I have purchased several model shots from is
posespace.com.
NOTE: This link does take you to a site with nude models. They have a variety of models and the 360 degree views means you can do a variety of drawing from a single model. The nice thing is, a series of shots costs around $5.00 and you get 8x10 @ 300dpi resolution.
It is not a bad substitute if you are itching to draw and don't have a live human: