"Be more disciplined", "work on my confidence", "stop procrastinating" — personal development goals usually arrive as moods rather than goals, which is exactly why they're so hard to act on: there's nothing to schedule, nothing to check off, nothing that tells you in three months whether it worked. A feeling you'd like to have more of isn't something a calendar can hold.
The manual builder forces the translation: it makes you name an actual objective, then breaks it into milestones and the habits or tasks that build toward it — a specific book finished, or a habit tracked for six weeks straight, rather than "be more X" left hanging in the air. Once it's phased and dated, "more disciplined" becomes something you either did this week or didn't, which is a far more useful question to ask yourself.
None of this makes the change automatic (self-improvement is still mostly just repetition, done for longer than feels comfortable) — but a vague intention with no structure rarely survives a bad week, and a phased plan with habits attached at least gives you something to return to. Just try it: write the vague version down, then see what it looks like once the builder makes you get specific.