I encourage authors to map out their stories before they compose. A story is like a river, with twists and turns, surprise waterfalls and white water rapids in between placid, flowing stretches. A straight-forward story is not like a river. It is like a canal. No one wants to read a canal. No one puts on their shorts and flip flops, grabs their inner-tube and yells, “Let’s go ride some canal!”
In each chapter or section of your book there needs to be a conflict, an obstacle your heroin/hero needs to overcome. In the first act, the hero/heroin might do well against the obstacles. In the second act, they need to fail. And the third act is where they have learned their lesson, gained wisdom, and finally triumphed over their adversary, or died a glorious death that inspires or educates others.
Unless you are quite experienced in story crafting, this structure does not flow naturally. This is why I recommend some form of story mapping. It is best to do it before composing, but it can be done after a first draft, during self-editing.