But I’ve decided the most common problem for first time authors is their inclusion of an unrealistic, unworthy, or absent antagonist.
Yes, your hero will always be his or her own worst enemy, but you need an antagonist to help your protagonist realise how strong he or she can be. There is no conflict without an antagonist. There is no reason to write a book if you do not have an antagonist. It would be easier to write a diary or an essay. Imagine watching The Matrix without Mr. Smith. The antagonist provides physical and psychological setbacks. He or she introduces points of resistance and stands between the protagonist and his or her story goal.
The antagonist’s function is to try to prevent the protagonist from achieving his or her story goal. The antagonist raises the stakes for the protagonist and causes excitement, tension, and a plot.