You
have a right to experiment with your life. You will make mistakes. And
they are right too. No, I think there was too rigid a pattern. You came
out of an education and are supposed to know your vocation. Your
vocation is fixed, and maybe ten years later you find you are not a
teacher anymore or you're not a painter anymore. It may happen. It has
happened. I mean Gauguin decided at a certain point he wasn't a banker
anymore; he was a painter. And so he walked away from banking. I think
we have a right to change course. But society is the one that keeps
demanding that we fit in and not disturb things. They would like you to
fit in right away so that things work now.
— Anais Nin
There is something to be said about the personal right to change course. The only person who can live your life is yourself.
The main characters of LOST were an unhappy group. They were troubled by their personal problems, career ruts, and family issues.
Was Jack happy being a surgeon? Yes, he was good at it - - - a miracle worker - - - but he did it to get his father's approval, which did not happen.
Was Kate happy as being a runaway criminal? Yes, she was good at it - - - a real Houdini - - - but she she did it to get her mother's approval, which did not happen.
Was Locke happy with his clerk job at a box company? Yes, generally since he had no motivation to do anything more since he was wheelchair bound. But his plight was the direct result of Locke trying to win his father's approval, which did not happen.
Was Sawyer happy being a con man? Yes, he was good at it - - - a smooth operator - - - but he did not get what his original objective was, that being to seek revenge on his parents' con man, Anthony Cooper. Sawyer would come to terms with Cooper only after Locke summoned him to the island.
Was Sun happy in her marriage? No, she had planned to flee Jin at the airport, but at the last minute, perhaps because of guilt or family honor, she stayed with her husband, dreading the future with him.
When everyone boarded Flight 815, their lives were pretty much set in stone. They had forgone change in their lives. They would continue to be stuck in a rut. There was no motivation to change the direction of their lives.
Until the plane crash. The island turned into a summer camp experience for the unhappy souls. As Jack stated early on, a person's past was no longer relevant on the island. Everyone had a chance to be someone different. Second chances don't come along very often. Jack was aware of it. He wanted to make the most of it. And he did, by doing something his father criticized him the most: not being a great leader because he could not make the difficult life and death choices. In the end, Jack did make that ultimate choice, sacrificing himself so a few of his friends could escape the island.
Whether that was true change or a mere diversion is debatable. Even if it was a sidetrack like the sideways world, then at least a part of Jack changed as a result. And maybe that is the simple lesson of the show: any change is possible if you want to change.