That's the all important question isn't it: Will there be any recognition of my existence in this world? - Will I produce or contribute something that people know me for and what will I leave behind when I'm gone.
I often ask myself these questions assessing my own self worth. But at the end of the day, it's not really something you can force. Hard work can help make things happen, but at the end of the day you may find yourself living a very unfulfilling life if you focus on it too much.
It's important to find a source of stable and reliable income in order to be comfortable in life. If your chosen career path facilitates the opportunity to contribute something truly great to, or recognised by, society, then great! But more often than not you will have to look to do that in side activities you choose to do, which is also ok.
The ideal career path is something where you do something you enjoy, are good at and that yields positive and memorable results for society. Often this ideal is not really available and compromises have to be made. I watched a talk given by Corey Taylor at Oxford University. He essentially said, "Do the things you are good at and even if you don't enjoy them so much, you will find enjoyment in achieving good results." This is a compromise that I can kind of understand and makes sense to me as I enjoy the feeling of reward from being good at something, despite it not always being enjoyable when I am doing it - for example my D of E hikes and expeditions. Conversely I enjoy drawing but being a perfectionist I don't really think I'm all that good at it and I don't like the results. So in the long run, what would I make my career choice out of the 2? - probably the former. There are obviously things that fall midway - I'm decent at drums (I think) and I enjoy playing, but to me drumming is not a stable career.
I'm lucky because I find medical science interesting and I do well enough at it, so I can make a happy career out of that, as well as do the things I enjoy on the side.
I like the suggestion that was made to have a career that can subsidise the things you enjoy and want to work on, which could lead to success but are a bit too unreliable to make into your actual career. At the end of the day, you don't want to be in a situation where you regret not making opportunities for yourself or not taking the opportunities presented to you, and in my mind there is no better way to facilitate that than to have a stable security net. Put 100% effort into everything you do, be friendly, helpful and live life to the fullest and its highly possible you will be the cause/creator of something worthwhile in this world.