Horses are very complicated animals to draw, especially since they are so bony. All of the tips for drawing humans applies for drawing horses as well too!
You can try tracing the shapes of the horse images you are using as reference with tracing paper or another layer (if digital). Doing lots of tracing will get your hands and brain used to the shapes and angles of the animal, without putting in a lot of "effort".
You can do 30 second gesture drawings of horse images, just to get loose and capture the energy of horse shapes.
However, at some point studying the muscles and bones (using an anatomy book or images of horse anatomy online) will get you much further.
Josh Papaleo has a 26 minute Youtube video on drawing horses and you can draw along with it!
I'm excited to see your horses improve :)