The Well-Rounded Homeschooler

I'm heading to the Refresh Retreat this weekend as a speaker.
One of my passions in homeschooling is Interest Led Learning - I will be giving a talk about how anyone can weave Interest Led Learning into their days - no matter your homeschool style.
Naturally I've been thinking a lot this week about Interest Led Learning, and also about the well rounded homeschooler.
What does being "well-rounded" mean?