On a related note, I attempted an answer on the question: What causes a person to be curious, inquisitive and explorative?
The younger generations (like mine) have developed in an over-stimulated environment. We are no longer satisfied nor amazed by simple things. As budgets for show-business and entertainment companies grew, so did our standards for amazement and wonder. 
In our increasingly complex world, the amount of information required to master any particular discipline — e.g. computers, life insurance, medicine — has expanded geometrically. We are forced to become specialists, people who know more and more about less and less. 
Like this quote denotes, I sometimes feel that everything is already explored or have been done before. This vision often cause a reflex to search for existing answers before even tackling a problem on my own.
He continues by saying that we are not going to school because of an initial desire to learn and understand the world, but because the existing world wants us to learn what it considers important:
In this frightening new world, students do not turn to universities for mind expansion but vocational training. 
Factors of influence
Motivation (in any flavor) can be influenced by personality characteristics, environmental factors and social situations. For example, there is a negative correlation between being in a depressed state and demonstrating curiosity in general.
It has been suggested that a decline in curiosity is one characteristic manifested by depressed individuals. [...] Results indicated that subjects made temporarily depressed reported significantly less state curiosity, perceived value of information, and desire for additional knowledge than elated or neutral subjects. 
Now if we look at Maslow's hierarchy of needs, it seems obvious that people with less satisfied needs are not naturally led to be curious. This implies that any society, family or individual that never approves the work of others, that can't provide security or food to its members doesn't provide an environment suitable for curiosity to develop.
There might also be physiological and developmental predispositions to grow up curious about the world. You can read more about these here and here.
The next section is highly subjective as it contains personal opinions
While there are things you can do to increase the likelihood of becoming curious about a particular subjects, I don't believe curiosity is something you can unlock with a magical treatment. Don't force it. It develops with time and new experiences.
Thing I would suggest:
Making practical uses of a subject, making links to other subjects you are already interested in. For instance, I became highly motivated in math and physics classes after finding an application for it in 3D game development. On another note, some people tackle life's problems with metaphors of things they know well.
Breaking the desire for stability, security and familiarity. Here is some media on the subject: Sell your crap. Pay your debt. Do what you love, Fuck your comfort zone.
Learning to learn (as stereotypical as it may sound) and doing things that you love.
Surround yourself with curious, motivated and interesting people. It will lead to very interesting discussions and you will learn lots of stuff from each other.