Do you even want to change it? It doesn't sound like it to me but you have no moral obligation to change the world or save it or start a business, be a leader, etc.
Being "great" is hard work, not all its cracked up to be and may not make you any happier than you are now and its not for everyone. Not to mention that "great" is a normative concept and who's standards are we talking here, yours or others? Do you want to be perceived as great in the eyes of others? Many people do and they "succeed" but it doesn't make them happy. At some level maybe you know that you are talented enough to be good but not talented enough to be great even if you applied yourself 100%. Perhaps you hold back for ego-protection and don't apply yourself lest you discover this fact.
You can see that your question is a bit complex and ultimately can only be answered by you. Nevertheless, I think I can help you in your quest by sharing an observation I've made about others. There are at least two types of fundamentally unhappy people as far as I can tell. The first type (I mentioned above in my first paragraph) are people who have no real self, no standards and just seek, in various ways, the approval of others. It is sad but I know many outwardly successful doctors, lawyers, business leaders, etc that are miserable because they thought being successful in the eyes others would make them happy.
The other unhappy class that I observe are people who ended up in jobs or situations that are significantly below their ability. These are talented people who never applied themselves, coasted through school and early life and then one day found themselves trapped by their poor decisions. They failed to apply their talent, to define who they are and what they would be and make an effort to achieve it. This is the auto mechanic who could have been an engineer or the grocery store clerk who could have been an electrician or a businessman or the plumber who could have been a writer, etc. It is a special kind of hell to be more talented than your job requires and many of these types resort to alcohol or weed to ease the pain.
(The unhappy doctors and lawyers do too but the requirements of their jobs tends to limit the extent of their drug use)
My advice is to find a career commensurate with your talents in a field that you enjoy and don't worry about what others think. These are the happiest types in my experience.