Hi Thephilistine!
You have a good start and you will improve if you keep going. After doing gesture drawing for a while you will learn to calm down as you draw, even very quick poses under 30 seconds. The key is not to draw more detailed depictions but rather to show more by generalizing what you draw. It is a good thing to warm up by drawing C and S shapes all over a paper again and again going both ways using light strokes and heavy strokes. This will loosen up your drawing arm and also make you more precise so that when you want to put down a stroke later, the stroke will land exactly where you intended it to.
Check out how Stan does it. See how few lines he is putting down and still manages to capture what the pose looks like:
https://youtu.be/74HR59yFZ7Y?t=205