“I’m happy,” she said with a smile. Yet, the sides of her eyes didn’t crinkle. She rubbed the back of her neck then crossed her arms. She refused to look at me, but I could still see her glassy eyes.
Reading the above, do I need to spell out that she’s lying? That she clearly isn’t happy? No, but why? Body language. She can say whatever, but actions will always speak more than words.
It’s important in writing to understand the different effects of different emotions. You need to be able to captivate their real feeling without a word of dialogue to support it. These are some charts from Pinterest I found to be useful. They explain well different kinds of emotions and natural reactions.
Are they lying?
Where do they feel it?
What does their fidgeting show?
What does their face show?