Creating Characters: Motive

Every character, minor or major, needs a motive. It’s the driving force behind everything they do.
In other words, their reasons. That’s all good and fine, but what it really boils down to is that there are consequences to their actions.
I cannot stress how important motive is. If there’s no reason your character should be doing something, then why are they doing it? Unless there’s a motive, your book will end up as pointless as a kid’s menu maze.

Courtesy of Applebee's

Self Interest
Face it. The human race can be selfish. But there’s a fine line between selfish and smart.
One of the most overpowering motives for a character is death. Most characters desperately don’t want to die. Death is the reason they do things they know are wrong, because self-preservation kicks in.
It doesn't have to be that extreme. Lying and cheating are things we do because we're afraid of the consequences.
This includes personal goals.
Other People
If humans were entirely logical we’d never risk our lives for someone we love, get angry, or set off on quests with only faith to guide us. If Spock needed to find the Holy Grail, he’d make sure of its location and existence before he went after it.
For the sake of a good story, humans don’t think in pure logic. We think about others. We do so many crazy things, good and bad, because of other people.
Your main character might risk his life for the woman he loves. That’s good.
He might get angry at a minor bad guy and accidentally spill the beans. That’s bad.
But either way, his actions are affected by other characters. The reason he acts is because of someone else.
Even the villain can be affected by others. Take Voldemort. He is so intent on killing Harry Potter himse that he spends far too much energy preparing a secluded trap for Harry and not enough time protecting all his lovely horcruxes.