I can change you know, when you stop to think about it, it's surprising how much time and effort we put into trying to change other people. If you have ever tried to push a wheelbarrow full of bricks you will find it isn't easy to get it moving. It's not Newton's fault, really, he just noted these laws. And, unfortunately, these laws of motion also apply to the behavior of people.
People tend to keep doing what they have been doing.
And it takes a very big tasty carrot or a very large and scary stick to change behavior. It is not enough that my behavior makes me uncomfortable - it has to hurt. It is not enough to see a slight reward in the future - it has to be a big reward and the sooner the better. And because I don't think change is an easy option I emphasize good hiring to my clients. You can hire that unmotivated shy person for your sales position, and change those traits, or you can hire someone who is outgoing and motivated to succeed.