How do I handle a long gap on my résumé? - first time posting

I have been out of work for 4 months and worry about the gap. Any experience at all would help. I am nervous about being filtered out. How did you handle it on your résumé?

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

Keep your skills fresh and mention anything recent. It shows momentum.