One difficulty that comes up often is how to manage failure. I am reminded of Asimov and his thoughts on this issue:
The writer's life is inherently an insecure one. Each project is a new start and may be a failure. The fact that a previous item has been successful is no guard against failure this time.
This is one of the most effective ways I have seen anyone describe the issue of failure in the context of art. Although he references writing, you can easily replace writing with any other creative craft and have the quote still make sense. No matter how much I seem to improve at creating art and no matter how much people enjoy my work, I struggle with insecurity and fear of failing. The fact that previous works have been mostly successful doesn't immunize me from these emotions. Previous success lessens the intensity of the emotions somewhat but the underlying fears never seem to go away. If you realistically look at each new piece, there is clearly a chance that you will fail, especially if you are constantly pushing your boundaries and taking on challenges that are potentially outside of your current abilities. I am not saying this to justify these insecurities but as a way to more objectively look at the issue.
On a related note, how do you define failure? It's tricky. For me, "failing" on a particular piece is not having it create an emotional connection with the viewer. How do you define "emotional connection"? This is a difficult issue as well. The way I define it is what the natural reaction of your audience is. For instance, if upon seeing your work, the viewer looks genuinely impressed, then you likely captured something important. Often times, what this looks like in practice is the viewer being somewhat mesmerized and not saying much other than "oh.." This sense of awe can take on different forms but it's one of those reactions that is in the "you know it when you see it" category.
Is the above definition of success too stringent? Perhaps. But if your art doesn't connect with people and move them in some way, what value does it have? It's true that the process of creating any particular work is essential for learning and improving your craft and I am not denying such benefits. I believe such practical uses of a "failed" piece are very important. But, such "behind-the-scenes" benefits are for the artist alone and such details are irrelevant for the audience. What the viewer generally wants is to feel something when they look at your work. When they don't feel anything, there is no way to hide it. It's very easy to see that it didn't do anything for them.
So, in the face of repeated defeat, how do you maintain motivation and persevere? How do you keep going when failure can feel so draining and demotivating? Unfortunately, I don't have a clear answer. From my experience so far, the primary reason why I am able to keep moving is because my love for art seems to be much greater than the sadness and frustration caused by setbacks. Additionally, as I do improve, my work is able to create an emotional connection not just with others, but with me as well. This connection with my own work creates a sense of fulfillment and meaning. These positive emotions feel wonderful and it motivates me to keep trying and not giving up because I want to keep experiencing such feelings again. Also, I try to remember that failing is an essential part of challenging myself and if I am not failing, it very likely means that I am staying in safe waters and not letting my ship sail farther out to sea. After all...
A ship in harbor is safe — but that is not what ships are built for.