The way I see my progress in hindsight is that the early years are the worst years, and you slowly but surely progress to not perfection, but a much smoother process of learning. You eventually know exactly what you did wrong and you don't need hand holding from mentors as much any more.
But it's not all that bad! The answers are often right in front of us, we just avoid doing what we know we actually should out of the anxiety to fail. If you struggle with something specific, grind the hell out of it. Don't take your time, if you know you can't draw it then you're supposed to suck 500 times until you get it right. So don't spend hours making yourself angry trying to perfect a single drawing you don't understand. Sketch sketch sketch sketch sketch! Get the numbers out to get the progress out.
As for the motivation part, I think that's a little more personal. I only have the long haul in mind, which is acquiring the skill to create my comic at the level I dream of it being at. So it simply means practice practice practice. I think what helped the most if shifting my mindset from "I need to be perfect" to "I need to fail". However backwards it may sound, the latter is what gave me the most enjoyment out of learning because there's no pressure. If there's no pressure, I can draw as badly as I want. If I can draw as badly as I want, I can draw as often as I want. If I can draw as often as I want, I get the progress I need. : - )
I actually can't stress how critical that is! Comic artists are combining a hodge podge of various skill sets together. By studying artists who highly specialize in just one of those aspects, you're getting the most bang for your buck in regards to learning. Comics can teach us how to put it all together but they're still abstracting and personalizing for what they want. Being open minded to external inspirations is crucial to your development.