What's in an emotion?
Emotions are powerful. They often drive our decisions and cause us to react to situations differently. If that is true, then emotion drives a story.
Look at the photo. How would you feel as you stood on one side of the bridge? Are you curious or are you afraid? Don't just think about your emotions. Focus on how your body reacts to those emotions. Do you squeeze your fist in determination? Or does your hands shake with fear? Does your throat go dry? Or do you take a big gulp of air? Do you feel dizzy? Or do you stare, trying to see through the fog?
Then consider, what is your next step? Do you take a step forward to see where the bridge leads? Or do you step back and consider going home? Why? What is driving that decision?
Every character, like every person, is going to respond differently. Their emotions will be different. Their body responses will be different. And their decisions will be different. For every character you write, put them in a similar situation and see how they will respond.
WRITING PROMPT: Before you start writing a scene, chose an emotion you want the reader to feel while reading your story. Be as specific as possible. Write down a list of words you can use that evoke that emotion. Then put your main character into that scene. How will he or she respond? Does it match your character's personality? Does it stretch him or her to their limit? Then, write the scene.