It is said that successful people are quicker to make decisions (larger than normal decisions, not the day-to-day factions of life) but are slow to change those decisions once they have been made. That being said, the rest don't make any decisions that could impact their life, and if they do, they're constantly changing them and never sticking to one thing for very long.
Growing up, there are many "careers" I wanted to do. As a child born in the early 1970's, I loved the Rocky movies. The second one was my favorite, starring the ultimate Mr. T as one bad-ass character. Anyway, I wanted to be a boxer. So, I woke up one Saturday morning and started training, just like Rocky Balboa. Wouldn't you know, it was a lot of hard work. I ran around our house about 6 or 7 times before stopping, completely exhausted. My boxing career was officially over. As a fan of the Indiana Jones movies, I of course wanted to be an archaeologist like Harrison Ford's character. But when I did a little research into what archaeologists do, none live the kind of adventurous life he did. Which is probably a good thing, I guess.
What does all of this mean? Had I stuck with anything for very long, I would've gotten better at it. Maybe not the Indiana Jones thing, but I think you get the point. Most people flit around and try so many different things that they never stick with anything long enough to get even mildly competent. I've met a lot of people who want to be a writer. Great. What's the problem? They may have a story to tell (and it could be the next instant bestseller too!) but they never start. Oh, they may write a dozen or more pages, even, but that's it. They move on to the next get-rich scheme.
Bottom line: make an honest decision about what you want to do. I don't care what it is. If you want to be an auto mechanic or a stock car driver or a janitor, that's fine. But work hard and be the best mechanic/driver/janitor that you can be. Martin Luther King Jr. said it best by this quote: “If a man is called to be a street sweeper, he should sweep streets even as Michelangelo painted, or Beethoven composed music, or Shakespeare wrote poetry. He should sweep streets so well that all the hosts of heaven and earth will pause to say, here lived a great street sweeper who did his job well.”
Find out what you are best at . . . and do it. Today. Right now. Even if you completely suck at it, roll up your sleeves and do what it is that you are meant to do.