I sit in a weird space when it comes to this. I lead a jam packed life full of "chasing my art and living the dream", but I also experience the overwhelming feeling of I can't all the time. Let me tell you, I wouldn't be able to get past this if I didn't have such a lovely and supportive network. I would curl in a ball and cry all day. I would take a normal job I hated and stagnate. I wouldn't travel, I wouldn't see people. I would completely and utterly give into I can't.
But I don't, because I'm supported and privileged. I think more people who say no to "I can't" need to be introspective and examine their privilege, especially before they preach the word of "everyone can do it", because not everyone can do it. It's not ideal, but it's one of the truest truths in our weird society.
I suppose the conclusion is, if you give into your feelings of I can't, don't feel bad. Don't feel worthless, because you're not. Breaking out of I can't is hard. And if you're one of these wonderful amazing people preaching the word of "everyone can do it" stop and think about all of the help, support and circumstances you've experienced to get you there, and consider how different the experiences and resources other people have are different.