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I get it, but drawing people while they're drinking coffee or something is invigorating! Haha. It's still an introverted activity and will boost your skills quick.

Drawing from a window would be good :-) But you are right, it is a great way of training fast accurate drawing.

I completely agree. I like to sit in my car before going into the grocery store and draw people as they walk in and out. Allows me to get lots of practice, have lots of subjects, and still be introverted.