The way to achieve that, in my opinion, is to try to align the person's career objectives with the company's objectives. Find out what motivates them, money, recognition, etc and illustrate how they can achieve those goals by achieving the company's goals. Then people motivate themselves.

The other part is being a good coach, which is not about giving advice, it's about helping someone take responsibility for their tasks and helping them learn how to improve.

That's just my opinion, and I'm not a manager so maybe I have no idea what I'm talking about.