Human traits are a vast shade of grey, neither black nor white. There is no one-size-fits-all approach. Someone who even attempts this approach is underestimating our diversity (not to disparage this scientific study in any way).

Focusing on 'dreams', focusing on 'flaws' or using some other emotion to motivate a person, there cannot be a 'standard' approach. Sometimes it is the 'fear of loss' which works wonders. On someone who wants to be the 'best', it is realization of flaws which might work. But there are several other factors which need to be taken into account, including life circumstances. Keep all options open and be willing to change your strategy quickly in response to how the situation is turning.

And sometimes, even if we want to change, the 'monkey' inside us doesn't let us change. Mere realization of a flaw does not guarantee change. It takes a lot of hard work to achieve a personality change. A lot of people aren't capable of that.