It probably depends on the codebase, but I find the best motivation for writing solid commit messages is reading commit messages. Tools like gitlens make this really easy.

Almost daily, I use commit messages and history as part of understanding why a decision was made, why a seemingly obvious alternative wasn’t chosen, etc. seeing the commit title on every line, and hovering to see the full message has become a core editor feature for me.

It’s kind of like testing, the more I do it, the more I want to do it because the value is so consistently reinforced.

There’s nothing like being able to track down exactly why a decision was made 6 years ago in a part of the code base you are struggling to understand written by someone who left before you joined the team.