Triggering the person's to think and be more creative requires special skills from leaders. Making the person owns the solution to a task will build self-esteem and confidence. Most managers and supervisors forgets that human tendencies are more incline to the personal aspect of their being.
To tap the creative side of our subordinates we must be able to challenge their mind yet not pressuring them.
Asking the question rather than using a declarative statement is usually more effective because it gets people reflecting upon their situation. We can't motivate anyone to do anything. They have to motivate themselves. And they best motivate themselves when they reflect on their character and their situation. The question prompts people to answer, and when they are answering, they may engage in such reflection. You may not like the answer; but often their answer, no matter what it is, is better in terms of advancing results than your declaration. Also, their answering the question may prompt them to think they have come up with a good idea. People are less enamored of your great ideas than they are of their ideas, even if those ideas are simply average.