For the last few weeks I have been successfully blocking time wasters via DNS using nextdns.io.

The nice thing about this is that you can't get around it by altering anything that you are doing on your computer other than changing DNS settings. For example if you are using a browser extension you could have switched to a different browser.

Perhaps because I am independent/rebellious by nature it is helpful that there isn't a program actually telling me that it is blocking me.

It also helps with a layered approach: you can use this with any other tool such as a browser extension. Another simple layer that I like to use is to locally remove some sites via an /etc/hosts entry.