Lead by example! Write comments half a page long or longer, explaining things, not just expanding identifier names by adding spaces in between the words.
I have mixed feelings on this. In most respects, I am a diligent worker who tries to lead by example. On the other hand, part of my work is managing people. While I have employees who follow my example, even when I am not intending my habits to be an example, and I adore those employees immensely -- I also have to face the reality that very few employees do so. They need direction on what is expected. Even then, the direction has to take the form of intense instruction otherwise ... woosh ... the details go over their heads.
That, and I have mixed feelings about commenting code. (Thankfully I don't managed developers. I simply exploit personally since it a skill that I have.) I understand why we do it. I especially appreciate well documented libraries and development tools. On the other hand, I fully understand that comments only work if they are written, read, and updated. The order is important here since documentation will only be updated if it is read and it will only be read if it is (well) written. Even then you are lucky if well written documentation is read.
The flip side is that comments are duplication. Duplication is fine if they are consistent with each other. In some respects, duplication is better since it offers multiple avenues for understanding. Yet there is also a high probability that they will get out of sync. Sometimes it is "intentional" (e.g. someone isn't doing their job by updating it). Sometimes it is "unintentional", since the interpretation of human languages is not as precise as the compiler's translation of source code into object code. (Which is a convoluted way of saying that sometimes comments are misinterpreted.)
Generally, high standards can only be achieved through enforcement, not merely through begging and pleading.
I like to add myself as a mandatory reviewer of all PRs and then reject changes that don't come with some explanatory comment or fail to update comments.
Even if huge swaths of the codebase are undocumented boring boilerplate, you still have to draw the line somewhere, otherwise you get madness like ten pages of authentication and authorization spaghetti logic without a single descriptive comment.
That doesn't justify matching their sloth.
Lead by example! Write comments half a page long or longer, explaining things, not just expanding identifier names by adding spaces in between the words.