Tension may be something you don't need in your life, but it is necessary to a good story. At the con I attended recently, an agent on one of the panels said, "Nobody wants to read about nice people." It may be a sad commentary on life, but it's true. Tension in a story pulls us forward. We must want to know how that tension will resolve. And it's certain that characters who spend time together will experience and react to their differences.
I've been working on that with my WIP. I like the story a lot, but readers tell me it lacks tension between the protagonists. While they are in danger throughout, they're pretty sweet to each other about it. So they have to become more tense, like the rest of us.
How to do that? I'm finding that I have to take a scene and put myself into a character's head. What would irritate me about a person who did this or that? What might I say that would in turn irritate him? While there are big things in life that we must deal with, it is often the day-to-day eccentricities of our friends and relatives that we struggle with. We accept the fact that Relative A is going to be late, no matter what the occasion. We know that Friend B will manage to bring up her generous chest size whenever possible. Do we scream at A or simply tell her dinner will be at 5:00 and plan on 6:00? Do we steer B away from discussions of body shape or simply roll our eyes and let her have her moment? How people act can create tension, and how we react can add to it.
So I'm role-playing in my head. Character C wants safety more than anything else in life. D craves excitement. If they have to co-exist, how do they deal with each other, what would they say, how would they each try to change the other's view? Then you can add other people to the mix, people who must get along with both of them and who may try to explain one to the other. These people too, have agendas (we all do) and could become irritated with one, the other, or both. More tension. If I can keep these threads going through the piece, the reader should get a sense of reality, of people who are basically good people but not unaware of each other's faults.
Once that's established, then there's how they say what they say. I'll shoot for that one tomorrow.