It may not be what you think it is
I think one of the greatest issues with the word "success" is that the modern definition of it has been wildly distorted to a point where it is practically unobtainable.
Modern media shows us success in the form of AAA Hollywood actors, or chart topping musicians, or billionaire tech company founders. In reality these people are aberrations.
Anyone who has ever studied statistics can tell you that the first thing you do with a bunch of figures is, pretty much, ignore the very extreme examples at both ends. So out of a planet of 7 billion people a few hundred who are massively successful in their creative field are largely irrelevant to what normal people can achieve. And yet we set them as the bar we are supposed to reach.
"Aim high" is a reasonable and useful thought process when you start a creative career. Ambition can be a really good thing if it motivates you to work hard and helps you focus on a goal. But aiming to achieve a level that is essentially impossible means you may never be happy with the things you do achieve.
We can get trapped, forever looking to the top of the success ladder. I find myself often discounting achievements I should have celebrated because I was too busy looking to the next thing. It is really important to stop, look at the things we accomplish and acknowledge their significance.