Maybe you can empathize with me? I have considered myself more of a "Jack of all trades, master of none" for much of my adult life. I've rarely been able to stick with any one thing long enough to get really good at and become "successful" at it. In fact, it often seems like I get bored and move on to something else once I start to become good or successful at it. This has been a source of great stress in my adult life.
When you're a child, you're encouraged to play and explore new and various things, but by the time you become an adult you're expected to choose one thing and stick with it. Our modern society (as opposed to societies that existed during the Renaissance period for example) strongly encourages and rewards specialization. I think this has a lot to to with the Industrial Revolution and the invention of ideas like the assembly line.
I've often wished I could be more like people like Tiger Woods who just seemed to know the one thing they wanted to do from early childhood. There's even a story out there about how Bill Gates and Warren Buffett agreed that the main trait that led to their extraordinary success was their laser focus. But you can't completely change who you are.
Tim Ferriss offers a way to reframe how we think about those of us who can't seem to focus on just one thing. Rather than think of ourselves as "Jacks of all trades, masters of none", we can think of ourselves as "masters of some". In other words, while we may not be capable of laser focusing on one primary thing like some people, we can focus on a small number of things that we can become good and successful at. And if those things can tie together somehow, we can even create extraordinary success from that bundle of things.
The key to being able to do this is to train ourselves to focus on a small number of things and see those things through to what we consider successful completion. A couple of techniques you can use to help train yourself are Warren Buffett's 25-5 Rule and the Ivy Lee Method. These techniques are similar in that they force you define and narrow your priorities down to a manageable number. The real key to these techniques though is completely avoiding everything you have not identified as the current priority. I recommend using Warren Buffett's 25-5 Rule to define and prioritize your broader goals first. Then, create a list of a bunch of bite-sized tasks to reach your highest priority goals. Finally, use the Ivy Lee Method to prioritize those tasks each day until you've completed each goal.
A secondary key to success is maintaining or recapturing that sense of play we had when we were growing up. Reframe everything you do through the eyes of playfulness. If you're stressed about money and material things, think about how you can bring a sense of playfulness to that area. Meditation and daily journaling can help a lot with this reframing. One could argue that this key to success is even more fundamental than training oneself to focus. There are plenty of "successful" people out there who are miserable.
That brings me to one last-but-not-least key to success. How do you personally define success? Think about it, a lot. Is your definition of success the one society defined for you? Does that definition bring you joy? If not, take the time to create your own definition of success.