Product Manager's Personal Projects

I'm taking vacation next week. This time we don't plan to go anywhere far. Instead we intend to stay mostly in Ljubljana and just relax for a week (if you can call running full Ljubljana marathon a relaxation). When I was still wearing an engineering hat and an opportunity of some unscheduled time popped up, I always used it to do some personal project that involved some exciting fresh technology or acquiring some new technical expertize. But I'm not wearing engineering hat anymore and in the past six months I've focused entirely on product development. As I sit now thinking what I'll do in the next 9 days I began wondering what product managers do for their personal projects (if they have any at all). Any ideas or suggestions besides the obvious "why don't you just enjoy yourself"?