I use notational velocity for logging. Every day I create an entry with today's date. For example, today I am writing on "20170126".

I use it primarily as a todo-list.

Each morning I write down what I plan to do today.

I also try to plan each task in terms of time, so for example:

---

9am - 10am: work on task A

10am - 11am: look into task B

...

---

Then as the day progresses I mark down things as [DONE] when I finish them.

What's cool is at the end of the day you're left with a journal of:

1. What you intended to do 2. What you actually did 3. What you didn't do