There is a difference between writers and artists who like the idea of being one, and those who are the genuine article. Genuine articles are true to themselves first, and put the pretension aside. They simply have nothing to prove. They know they're an artist or a writer because art or writing comes as naturally to them as breathing air. It's in their blood. It's not something they have to struggle with. It's not something they have to strain over. It's a joy. And that's how it should be.
My personal belief is that, if you're trying too hard on a certain path, and it seems as if everything you're doing is wrong - when you're just not "getting it" - then that path is not right for you. Maybe you aren't meant to be a professional artist. Maybe deadlines and critiques are too much for you to deal with. It doesn't mean that you should give it up entirely, but that you should appreciate it for what it is, and stop trying to force yourself into a mold you don't fit.
When you find the path that fits you, your steps along it shouldn't be difficult. Sure, life will put some obstacles in your way, but you shouldn't be hanging on by your fingernails on a semi-regular basis. We all have those doors in our life that open for us, and some that we have to open ourselves (maybe with a crowbar). Sometimes we end up closing a door we thought would lead us to our path, but ended up leading away from what we really wanted.
If you stick to what you know, are good at, and what you love, you should find a career that's fulfilling and productive. But it's good to remember, the more doors you try, the more things you will find to love. We can either be freed or limited by our choices.
Once we find our path, the only thing that can really shake us is ourselves. For me, comparing myself to others can be my downfall. Watching someone else who writes, or someone else who illustrates too closely usually affects me negatively. I wonder "Is that what I should be doing? Am I not doing this right?" All the while the little voice inside says "Trust your instincts" and it's right, because only I know what's right for me in my own path. If someone uses a different style than me and is popular because of it, that doesn't mean I should adopt that style. If someone uses a different method to edit their novel and a lot of people agree with them, it doesn't mean that I should use it. Their novel is not the same as my novel. Their style is not the same as my style, and their methods might not work for me. Everyone thinks differently, and while it's good to listen to tips and mimic techniques, you don't come into your own until you rely on your own judgment.