Hi Elli - this is a neuromuscular and efficiency issue that will take time and practice. You will not just be able to "do it" - but will take some patience, training, and time.
I would look over my video's and watch the ones on cadence and start doing the drills in the videos. And of course, really focus on the zone 2-3 runs min the book's program. This will really help bring things together.
Keep us posted on how the training for this goes.