I also like SliTaz: http://slitaz.org/en, and Slax too: https://www.slax.org/
Oh and puppy Linux, which I could never get into but was good for live CDs: https://puppylinux-woof-ce.github.io/
And there's also Alpine too.
Booting a dedicated, tiny OS with no distractions helped me focus. Plus since the home directory was a FAT32 partition, I could access all my files on any machine without having to boot. A feature I used a lot when printing assignments at the library.