According to Newton's Third Law of Physica, "For every action, there is an equal and opposite reaction."
For instance, last week I was on a writer retreat, away from family with its attendant cares and woes. This week? No retreat, lots of family (and woes).
Last week, I wrote something like 6 poems in 4 days. This week? Nada. Niente. Zilch.
Last week, I woke early, full of energy and ready to write. This week, I'm tired. Tired, tired, tired.
Still, I'm off to get some writing done today anyhow.