What is it?
Intrinsic motivation is a very simple concept, that is quite difficult to understand.
Intrinsic motivation is doing something that is driven by internal rewards... or something that makes you feel good and gives you purpose. Relatively speaking, the majority of behaviours and actions in our lives aren't internally driven. Take, for example, reading a book. If you pick up a book and read it because you genuinely want to learn more you are intrinsically motivated. However, if you're reading a book to pass a course you are extrinsically motivated. Some other examples of extrinsic motivation may be familiar to you... exercising to lose weight, going to work to make money, studying to pass the course, or driving within the speed limit to avoid the fine. Are you mostly extrinsically motivated?
A behaviour that is driven by intrinsic motivation lasts longer and becomes a lifestyle change. Why is this type of motivation seemingly so difficult to experience? Why is this type of motivation so hard to come by?
Perhaps this blatantly stereotyped comic is part of the reason. That is, there is a huge 'grey area' of motivation. Some people may be intrinsically motivated by external things. I tend to believe that our society, one of overindulgence, is making this seem like the only type of reality. For instance, from a very young age we are taught to 'go to school' so we can get 'good jobs' in order to 'support a family'. Society fills in the blanks by shaping perspectives into thinking that 'good jobs' are those that are stable and high paying. Society shapes the perspective that 'supporting a family' means buying them things and going on nice trips. All of these perspectives are based on the fundamentals of external motivation. No doubt intrinsic motivation seems so foreign.
I think the most effective way to 'find' intrinsic motivation is to explore what is most important to you. Not just why you want something... but what is most important to you. Is your health most important to you, or is not having love handles important to you? Is getting a full nights sleep most important to you, or would you rather be able to gossip about the latest 'Bachelor' episode? Whatever it may be, you have to be entirely true to yourself when you answer these questions. The answers may surprise you.
Once you determine what is most important to you it will likely become more clear as to what behaviours you truly want to stick with.