Recently, I attended a leadership retreat hosted by the student life organization at my university. Personally, I grew a tremendous amount in the three short days, and wanted to include this experience in my resume, which is for another job also employed by the student life organization. As my experience is a bit lacking (only some tutor/mentor volunteering), I wanted to include this retreat and explain how it reinforce existing strengths, while also allowing me to discover new ones.
However, this is very outside the norm, as I couldn't find anything about including non-work experience; I only found how to include non-relevant work experience. As such, I'm a bit lost on the unspoken rules of resumes; should I include the retreat? How long and how detailed should I describe it? Or should the description be moved to the CV?