I'm a big fan of the writer Steven Pressfield. I've not read any of his novels (it occurs to me I should probably correct that soon), but his non-fiction really explains something I think is in all of us.
In what can really only be described as a trilogy — The War of Art, Do The Work and Turning Pro — Pressfield notes that the thing that keeps us from our calling, our love, whatever you want to call it, is Resistance. And Resistance can come in any form. Your family keeping you away from your easel. Your day job sucking up all your energy. Your overwhelming desire for a Big Mac being one more excuse to not sit down and write.
Anything that prevents you from doing what you really long to do, that's Resistance.
I was thinking about this in terms of Platonic ideals. If you're not familiar with this concept, here's a brief simplification. If you picture a tree, you form a picture in your head of a tree. You will probably never see a real (physical) tree that looks exactly like the tree you pictured, but based on the tree you pictured, you can classify real trees as being enough like the tree you pictured to determine they're all trees.
The tree you pictured was your Platonic ideal.
Pressfield imagines Resistance as a dragon, and you, as artist or entrepreneur or whatever, must slay the dragon to do the work you want to be doing.
I feel less Resistance than I used to. I'm certainly writing consistently. I've taken on some projects that I'm actually accomplishing. My money's being better spent than it used to be. I'm not sure what Resistance looks like to me, but it's getting weaker, or smaller. I don't know, maybe I don't need it to take on a form in order to defeat it.
What does Resistance look like to you? How can you defeat it?