I used to sit at home and decide what to do.
For me at least, deciding what to do is the beginning of procrastination.
So I no longer decide what to do, every morning I am at my desk at 9:00 am. I no longer have to decide this, because that’s what I do every weekday. For the first couple of weeks it was hard, but now it is just what I do. I no longer have to use up my limited reserves of self-control because this is my regular activity.
It seemed fair to me that I would be able to do a regular work day on my thesis. 9 to 5. It seemed impossible initially, but people that have real jobs can do 9 to 5, so I guessed I could too.
Next, I reduce the number of options of my activities while at my desk.
You might want to use software to help you. Freedom lets you block your computer and phone etc from accessing the web pages that you use to procrastinate. If you google block distracting websites and the type of browser you use (Chrome, Firefox, Safari) you will find plenty of plugins that will achieve that same thing for free. If you work on an institution computer, plugins like this can be easier to install because they may not need administrator permissions.
What choices can you eliminate for yourself that will reduce the number of ways that you can procrastinate?