I've read https://writings.stephenwolfram.com/2012/03/the-personal-ana..., have used Seinfeld calendar apps, and bought productivity tools... all with no luck.
I have an addictive personality so I could easily sit in front of the computer and write code for days on end and not take care of myself. This little physical book and pen is the only thing that's brought me back to reality and kept me on track!
The reason I ask is because I'm building something like this. And not many people track their habits as systematically as you do.