How do I handle a long gap on my résumé? - any advice?

My résumé shows a gap from a layoff and some health issues. I worked as a marketing coordinator before this. I am not sure how much to explain. What do you say in interviews?

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.

I listed the volunteering and course under the same dates and kept the explanation to a sentence in the cover letter.