I used a single log.txt file between 2005 Nov 4 and 2014 2014 Aug 11. This was instrumental in my professional life between those dates. Business ideas, call stacks of ViEmu bugs that I worked on, passwords, financial forecasts, bug and feature lists, database schemas, tracking of billable time for contracting and consulting work... can't recommend it too much. Having a single file is great, I had actually switched from having two separate log files, one from each project, which I had kept during 2005 (one for ViEmu and another for NGEdit, the text editor I was working in that never saw the light of the day but did give birth to ViEmu). Of course, I always edited this file under vim, "murphy" color scheme. A sample:

Sun 19-6-05 Researched (HEAVILY) how to do a "vi emulation module" for microsoft visual studio:
* Downloaded and installed VSIP
- Need: Visual Studio .NET CDs with C# (seems that C# will be easier)
- Install & compile some samples
* Create a new ViEmu sample
- We can "host" the Visual Studio text editor - using the "Data/View" separation model.
- We can follow the instructions on how to host it, but tell IVsCodeWindow to use a different
CLSID for the text views (IVsCodeWindow::SetViewClassID). It uses CLSID_IVsTextView by default.
- We implement a new COM object which is a pass through. It uses IVsTextView internally, and
we pass everything to it. We can call GetWindowHandle() on it to retrieve the HWND, and
install a message hook to process keys before they are sent!
- Implement VimEmu in C++

In 2014, I wanted something that would work better both on my laptop and on my phone, and I switched to OneNote. Several great things: text formatting, having separate notes for some things, good mobile integration back then. I tried several options mainly to make sure synchronization would work fine, and really poor conflict resolution on both Apple's Notes app and on Evernote got me to adopt OneNote. I've been using it until 2019, OneNote on MacOS has become basically unusable. Input lags like it's nobody's business, rendering it nearly unusable. Mobile does not work well at all any more, especially with large notes. The very non-standard document model together with their MacOS and iOS implementations make it unbearable. A pity, but I couldn't wait a few seconds for characters to show after I type them.

So, a few months ago, I went back to... using plain text files with vim. I missed some coloring, so I set up some autocmds to color buffers according to some rules. I'm using a few files (less than 10) to handle different projects and keep them separate, I miss the single file for searching and there are always items that overlap different areas, but i prefer it this way now - plus I do have a "main" catchall file (chautauqua.txt, after Robert Pirsig's book reference).

This kind of "journalling" is very useful but kind of addictive too, so I'm sometimes ambivalent about this. I did stop tracking my weight daily after doing it for about 10 years too, I like to stay aware of my weight and somewhat fit but I don't want to depend on a daily fix of a Excel spreadsheet to do that.

People, do journal and track things if you have never done it, it's a boon. Then find your best way, and maybe even do find the areas of your life you don't want to keep track of, there is something to be said for that too.