A leader does not only ask for a “last effort”, he creates the conditions worthy of the effort
Motivation is an essential part of life and success, and a leader may justly ask for one "last push", but the leader's job is more than that. The job of the leader is also to create the conditions that will make that push effective, to have a strategy worthy of the effort called upon.
The last 10% is 90% of the work.
It is a mistake to hire huge numbers of people to get a complicated job done. Numbers will never compensate for talent in getting the right answer (two people who don't know something are no better than one), will tend to slow down progress, and will make the task incredibly expensive.
The Brook's law states that when a person is added to a project team, and the project is already late, the project time is longer, rather than shorter. Brooks’ law is recognized as applicable to any complex endeavor involving lots of people interacting together, not just software engineering.
The results (ed. of the study): only 1 percent of the executives said managers should bother showing employees that their work makes a difference. If anything, many companies try to explain the value our work will have in our own lives, the benefits we will reap if we hit a goal, as opposed to the benefit that others will derive.
But remember our biology we are more inspired and motivated when we know we are helping biologically others.