I have found one of the most powerful tools to accomplish task appears to be the "one more thing". In particular, once the tools and setup are completed, everything that ever gets accomplished is simply only one more thing after another. They key here is the only. In fact, every single one more thing has its own cost, its own requirements. This is a beautiful thing when constructing a skyscraper, digging a trench, or eating an elephant.
A problem occurs, however, if you take only out of context. If you are en route to a destination, knocking out only one thing is never quick, never easy, and rarely results in the intended goodness. More often, there is a general lack of timeliness, a loss of some degree of freedom, and a propensity for procrastination.
Most uses of only are out of context.
A far more effective use of resources would be to either schedule the only or to simply wait for a better time.