more frequently voluntary discomfort is a manufactured excuse to bitch and complain so you get noticed

I think expectations matter quite a lot.

For example, when practicing a practical skill, the actual practice session itself will likely suck. Not only will you see no progress, you may even feel you're going backwards. You'll also get mentally and physically tired and quickly kinda feel like shit, even if it's something like penmanship.

The catch is that the progress happens between sessions when the brain is processing the new training data. If you don't understand and expect this, it's very easy to bounce off almost anything. If you do understand that this is the expectation, then it's much easier to accept the discomfort and stick to it long enough to actually begin to improve.