Hmm...at first I really liked the sound of this, but I soon started to find difficulty with it. First, the "rest" seemed a bit easier to define than the "work". That's because "work" can look like a lot of things - we defined church meetings, participating in the planning or doing of ministry activities, language learning, etc...all as work. But the truth was, a lot of things felt like work, and we didn't know when to rest.
When we first heard of this concept, we were still at the University doing language learning. We tried to be intentional about dividing our days up, but we were swimming in French work and couldn't find enough rest time. We were also trying to be very intentional about building relationships with the church community, new French friends and neighbors, and on top of that we were parenting JJ, and trying to find time together, as a couple. So, for a while there, virtually everything felt like "work", unfortunately. Even having dinner with our French friends, whom we really enjoy, felt like "work" because when we're with them, we operate in our 2nd language, which is "work" right now. And really, because the crux of our ministry is relationships, building relationships and being invested in them is work. Don't get me wrong - it's very rewarding, and this is how God created us to be - in community, but living in community is work.
Having said all of that, whether it's thirds, fourths, or taking whole days off, I really like the idea of dividing our days or weeks up somehow as a way of staying organized, protecting ourselves from working too much, not feeling guilty during our down times, and not forcing ourselves to be productive all the time. These are essentials to self-care and will lead us toward healthy ministry and lives on the mission field.