The more people understand the “why,” the big picture, the overall goal, the more motivated they tend to be. Actually, it is a form of respect, an affirmation of people’s value to include them in the bigger picture. There is not always time in the hurly burly of the everyday to stop and explain, but it is important to take the time. Indeed, when people understand the full “why,” you often get excellent (and sometimes humbling) feedback.
Let others know the WHY of what you are doing or asking. You will be amazed at how they will enthusiastically pitch in to help and will deliver a more effective effort.