Recently I've been getting the feeling that what ever I'm drawing is wrong and I can't seem to just let lose and go. It's stopping any type of creativity from coming out, all I seem to be able to do are studies, but those start wearing me down after a while. I can grasp an idea of what I want to do, like right now I want to draw an interpretation of Capaneus (a titan who lies in Dante's 7th ring of hell forever blaspheming against god,laying on the burning plains being rained on by fire)

but I can't get past the rough sketch/idea, I start drawing and I think the anatomy is wrong,then the pose is too bland when I have those, then I haven't paid any attention to composition so he's just lying there in the center, I can't seem to let go and just start doodling him, I can't spontaneously decide to give him horns "just because I can."

I need to stop over thinking things.

I've tried to just let lose and doodle, but I get irritated by how pointless and un-amounting they are

anyone else gotten the same problem sometime, tips for overcoming it?