5-Second Sketching Exercise For the Funkiest Style

Please take my advice with a grain of salt but I'm concerned this approach may develop some bad habits. Drawing fast and drawing with energy doesn't actually involve moving your pencil fast. That's a common misconception. Adding energy to your lines has more to do with the shape/tension (read: curve) of the line and the confidence with which it is drawn. Speed actually develops from getting good at placing well-considered lines strategically and efficiently, not from getting into the habit of moving the pencil around fast. I would suggest going no less than 30 seconds and practicing taking some time to look at the pose and then establish a primary line-of-action. Once that's confortable, start placing the head, then the torso, etc.

With regards to energy, try exaggerating the curve of the your line-of-action and then the subsequent secondary action lines to really push the motion and tension of the movement. A stronger curve creates more movement and tension while a more open line releases that tension. Use that to direct the movment. Again. The energy you're seeking IS NOT created by drawing fast, it's created by the choice of lines and the efficiency and confidence with which you draw them.