Grief and daily homework

I have a question re daily homework, specifically “how can you tell the story so it truly was good.”

My mother was recently diagnosed with terminal cancer and my dad already has a terminal heart condition. The other day was pretty rough for me emotionally and as I was trying to do the homework, I was struggling to find the good. When I tried to change some of my thoughts about my parents, they felt false. Positivity seemed too far a stretch. Since I think I am going to need ladder thoughts on most of what’s going on with my parents for right now, should I be focusing on a less serious, negative thing I am experiencing in the day?