How to make it easier to receive constructive criticism?

Typically finding out about the flaws in something that we did feels bad because we realize that our work was worse than we thought, so receiving the criticism feels like ending up in a worse state than we were in before. One way to avoid this feeling would be to reflect on the fact that the work was already flawed before we found out about it, so the criticism was a net improvement, allowing us to fix the flaws and create a better work.

But thinking about this once we've already received the criticism rarely helps that much, at least in my experience. It's better be to consciously remind yourself that your work is always going to have room for improvement, and that it is certain to have plenty of flaws you're ignorant of, before receiving the criticism. That way, your starting mental state will be "damn, this has all of these flaws that I'm ignorant about", and ending up in the post-criticism state where some of the flaws have been pointed out, will feel like a net improvement.

Another approach would be to take the criticism as evidence of the fact that you're working in a field where success is actually worth being proud about. Consider: if anyone could produce a perfect work in your field, would it be noteworthy that you had achieved the same thing that anyone else could also achieve? Not really. And if you could easily produce a work that was perfect and had no particular flaws worth criticizing, that would also be evidence of your field not being particularly deep, and of your success not being very impressive. So if you get lots of constructive criticism, that's evidence that your field is at least somewhat deep, and that success in it is non-trivial. Which means that you should be happy, since you have plenty of room to grow and develop your talents - and you've just been given some of the tools you need in order to do so.