Greater work on your anatomy on the subject's bones, muscles and subtler movement, that's very greater. However, I'm not getting broader enough strokes yet. How would and could you love to do some 2 hours of 30 second quick sketches? As a result, you could and should be the nicest to yourself, just so you would and shoud enjoy the process, but get the loosest and lightest and liveliest lines and shapes. For more information and details, please pick yourself up a copy of the Mattesi's Force Figure Drawing books on this website.
My hat's off to you.