The main motivation of Okonkwo in Achebe's Things Fall Apart is "to not end up like his father"
The explanation for this is that Okonkwo was a renowned leader of his tribe, as well as being a warrior and a successful farmer, but he lived in constant fear of becoming, lazy, cowardly and female like his father. This fear makes him make inappropriate, self-destructive and malefic decisions for those around him.