My current WIP has sent me through several psychological states: first elation, then dread, then depression, then elation again, and then probably bi-polar disorder. I spent nearly 6 months designing five separate solar systems complete with flora and fauna, alien races, cultures, history, and tons of other things that probably would bore you to death. I also spent a good month designing all of the main characters of my first book in the series, and even though I spent all that time on the main character (a rough-and-tumble bloke named Guillermo March) I realized today after finishing four chapters that I probably didn't spend enough time creating his motivation.
Sure, Guillermo lives in this very detailed and carefully constructed universe, but why should we care about him? He's one of 45 humans left in the universe, and trust me the backstory as to why he is would take up too many words for this post. He is the only human police officer to join the C'Tuulian (those are aliens) security force. He spent a full year undercover, working a complex sting operation to bring down a drug lord who was selling a deadly drug to a growing number of humans who felt they had nothing to lose, including Guillermo's wife who died of an overdose. He is present when the infiltration team arrives, but in the process loses his arm and falls into a coma, only to wake several weeks later to discover that out of retribution (or so the authorities think) the drug lord's lackeys set off a bomb in the human enclave, making Guillermo the sole member of the human race.
Again. Why should we care about him? I'm still working this out, but I think it might be rooted in his plight as the last human, his coping with the loss of his arm and its robotic replacement, his snarky comebacks that he uses to disarm those who would attempt to sympathize with him, and...well...I'm not sure yet.
I've written four chapters of this book at least three times now. At first it was the voice and point of view that soured me to it, then it was the circumstances behind the plotting, the reasons why the villains (and the villains behind those villains) were perpetrating the evil upon Guillermo's world. Some of the motivations didn't make sense. I think I've got that worked out now.
I just need to get Guillermo in shape. My desire for him as his creator is that he is believable, likable, and is driven by the three basic needs of hunger (be it physical or mental), to not be lonely, and to ease his pain. Perhaps he will need to suffer hunger, be lonely, and endure the pain to become more real.
The point here (in the middle of my rambling) is that your protagonist darn well better be someone the reader can care about or at about chapter three your reader will look for other stuff to read. It is a difficult conundrum. Think hard on this. Your readers will thank you.