Yah, I do that too. I'm just getting started in making comics so everything I make looks subpar in my eyes. But I focus on the feeling of accomplishment, the feeling of, "Yes! I'm actually doing this! And I am going to be committed. I AM committed!"
And as mean as this may sound, if I feel really down, I look at published/popular/professional manga that - to me - has crappy art haha For example, Attack on Titan is arguably one of the most popular manga internationally at the moment. But have you seen the art? For real, some people could draw better with their feet. Don't get me wrong, I love AoT (I draw AoT fancomic here on Tapastic, that's how much I love it), but when I look at the art...it's just...awful at times. Perspective? Psh forget that, who needs perspective? Fingers and toes? What are those? Just draw blobs or do the classic hide-them-behind-their-backs move. And the screentones...more like just varying amounts of grayscale. And yet, look how successful it is and how much I, personally, am obsessed with it. It just gives me hope that even if my art isn't where I want it to be, as long as I stick with it and make a story that's intense and intriguing, I'll get to the level I want some day~