Mary Casanova says, “We all struggle. We carry around inner conflict in the private places of our hearts where we search for our identity; we struggle with ego, pride, and jealousy; we cry out for love and yearn to be heard; and we try to listen to the small, still voice of God. The heart is a place of darkness and light, often in conflict with itself. It is from the heart that conflict originates and resolution emerges, and in the heart that change and personal growth occur.”
Caro Clarke says, “Conflict is opposing desires, mismatches, uncertainty, deadlines, pressures, incompatible goals, uneasiness, tension. We are all caught up in some of these conflicts every day. And, so should your characters. A convincing story has many conflicts built into it, layered and connected. The first layer is inside your characters. Once you know what these are, you can use them to make the conflicts between the characters more convincing and interesting.
“A character's inner conflict is not just being in two minds about something, not just being torn between obvious incompatibles (“I want to be a priest, and yet I love her”) but is about being in a new situation where old attitudes and habits war with and hinder the need for change. For instance, a man who drives himself to succeed because he doesn't want to be like his happy-go-lucky father is suddenly confronted with a situation where he isn't winning. Or an executive discovers that her ambition to be vice president of her company is being thwarted by her own self-doubt. This war inside each of your characters makes them act and react in complex ways.
“You show these internal conflicts not by means of internal dialogue (which is a cop-out and is dull), but by showing your characters responding to their own inner compulsions. She, for instance, decides to confront her own self-doubts by taking on a no-win project where the local people are opposing a development. She is determined to be hard-nosed, prove she's vice-president material. He is always confrontational, fearing that one minute of negotiation would be the first step to becoming a wimp like his father. You have a grade-A opposites-attract situation here, yet it is believable because we understand why each of them is acting the way they do, why they are foolishly stubborn, by it's important for each of them to win.
“A character's inner conflict can be between what he thinks he wants and what he really wants… Conflict must always be resolved, and every layer you create needs its closure. A satisfying and economical way of achieving this is to use one big knot to close two or more conflicts together in the same action or in a double whammy, where one leads ineluctably to the next.”