Somewhere along the line we forgot that we are Human Beings, not Human Doings. We are not machines, we have complex lives and not everything is predictable. I believe that we can trust life a lot more than we do, and that on those days - or hours - when the energy isn't there to do what we set out to do, it's best to honor that.
There is such a thing as "right timing."
If you wait until your energy is available, things will go more smoothly and quickly than if you push things through.
Honoring the ebb and flow of our available energy makes us more effective, not less.