One technique mentioned was delaying access to common timewasting sites. That is way too complicated and doesn't get the job done. Just put it in your hosts file and "block" it by pointing it at 127.0.0.1. If you really need access, "unblock" it by undoing that. This sounds stupid, but it really helps. Everytime you waste time at a site, add it. That works for most sites- not all, but enough.

Another technique mentioned was breaking tasks up into hour blocks with rewards. This sounds like Pomodoro technique. I tried that on multiple occasions and it never worked. The timer and breaks distract me and interrupt whatever flow I might have been lucky enough to get into. I've never worked with anyone that has continued to use this technique. Rewards in-general work, but I'd just have a reward when done with a task and have smaller tasks.

Here are other techniques that really work: (1) Find work you like to do and that you are good at, and find an environment where you excel. If you can't, then try to reduce stress through music, taking brief walks, etc. (2) Sleep more. (3) Lose weight in a healthy sustainable way. (4) Get exercise regularly. (5) Take care of your physical and mental health. (6) While at work, write down one thing you need to do. Finish it before doing anything else, unless there is an emergency you should assist with. Repeat.