I wonder what you've tried out! Personally, I believe in the ol' grinding method. Find time to dedicate yourself to drawing using models, real or not, and work on poses from 1 hour down to even 30 second changes. And you gotta remember the purpose: understanding how the body works. Drawing from models helps you capture the essentials while training your eye to examine why certain muscles/bones lay the way they lay. It takes time, but you'll discover details/shortcuts on your own that way!