I would suggest take life drawing courses or go to life drawing sessions in your community. Take out a newsprint pad and some conte and draw like you’ve never drawn before. It’ll really help you and you’ll get better at gestural drawings.
After that, for example, if you want to go to a ballet and draw the dancers, you can put it quick line of actions and do a quick gesture since you’ll be able to draw poses fast enough due to those unhealthy life drawing sessions. Also, life drawing sessions help because you’ll begin to understand anatomy and you’ll be able to see and a draw a person from different perspective. You’ll understand it well enough that you won’t even need a model. On your own time you will be able to draw the figure without even looking at a model.
I know its difficult, but it takes time and a lot of patience. Also, I wouldn’t recommend drawing from magazines, books or photographs because your drawings will seem flat. There’s a difference with drawing by life than there are with photographs. I don’t know what it is. But generally, drawings done by life have more movement or life to them.
Also, drawing by life forces you to draw faster.