When you love what you do, work becomes the highlight of the day. It's the time when you create art - something that's creative, passionate, and personal.
To quote Seth Godin, "Art is about intent and communication, not substances", and that "An artist is someone who uses bravery, insight, creativity, and boldness to challenge the status quo."
That said, such work demands energy, something that we have a limited supply of. Moreover, when the work is compelling, it demands your immediate attention.
That's a slight problem for artists. And if they let it, they spiral into a perpetual work-mode, up until they run out of energy. Neglecting family, friends, and god forbid, health, is a common phenomenon.
To such people: Respect yourself more by respecting the weekend.