Also had multiple failed journaling, reading, meditation, flossing, and exercising attempts, all of which have been fluctuating within acceptable bounds (e.g. some days I can only meditate 3 deep breaths) for the last 4 years or so.

This was a problem for me as well, but this post by Oliver Burkeman helped me take action and launch The Metronome : https://www.oliverburkeman.com/justdo

We can't act on every single idea we have, but it's better to bring at least one into the world than have several world-changing ones gather dust in a notebook.