Many of us are scared of heights, spiders and yapping dogs. We might be terrified of boats, riding on public transit or walking alone at night. The degree to which our phobias impact our lives varies from person to person.
Seeing any size dog might cause your character to cross the street or turn around and go back home. A spider crawling on the wall might temporarily freeze your character, increase heart rate and impact breathing, paralyzing her until she forces herself to grab a shoe and smash it repeatedly.
There’s a difference between not climbing a ladder and not going out after sunset. The first might prevent him from cleaning the gutters while the second might stop him from enrolling in classes at the university, accepting a longed-for job or jogging in a nearby park.
Your task is to write a story in which the phobia seriously impacts your character’s life. Perhaps if when she steps outside and hears a dog barking somewhere, she goes back inside and slams the door. Maybe she stays there, missing dinner with friends or even not going to work, which results in broken friendships or a lost job.
It might be interesting to hear how your character explains his phobia to others, so include dialogue. Sensory details will be paramont, so make sure we hear, smell, see, feel, and possibly taste very bit of that fear.
Have fun with this one.