M is for Motives and all characters must have them. Motive is a reason for the goal. Why does the cop want to catch the killer? Why does the heroine want the hero? There are dozens of other things that motive can cover.
Just as each character has a motive for their desires, so are there motives in the smaller scenes that occur in a story. Finding and making the motives or reasons clear for the characters actions and reactions is important to the story.
A weak motive can make a weak story and turn a reader off. When strong motives between characters conflict drama is born. So seek to make each characters motives strong. Remember even minor characters have motives and they can be in conflict with those of the major characters. For example, a mother can have a strong reason for not wanting her daughter to marry the hero. This brings her into conflict with her daughter, the one she wants happiness for.
So as you're writing look at your motives and make them strong and in conflict with the motives of the other characters.