How do I mention pre-grad school work experience on my resume?

I graduated with a B.A. in psychology and then got a master’s degree. Before I did so, I had work experience that really relates to the job I’m applying for, but it was before I got my B.A., say around 12 years ago. I don’t want to include this way back in my experience section, because it was so long ago. I also don’t want to omit it entirely because it is relevant to today and could help me in my search. What’s the best way to include this work experience?