Tracking feelings back to thoughts

I’m a new scholar, and learning the model. I am also using an urge jar and feeling what I’m feeling instead of buffering.
I have been curious about what I am feeling, which often seems to be “emptiness” or maybe it’s boredom. It feels like a heaviness in my chest, an aching. But although I allow myself to feel, I’m having a hard time figuring out the thoughts that are creating these emotions. I know I’m early in the process and just learning all of this, so I am giving myself time to learn. But I wonder what the process is to figure out the thought.
Should I try putting different thoughts in the model and see which seems right?