What if I only have one big thing to do? Now I’m working on the first chapter of my thesis.

You can always break big tasks down into smaller parts. And sometimes it helps to do so in order to stay motivated. For instance, you could say I am going to write two paragraphs, then I’m going to spend 30 mins collecting and organizing source material for the next bit and then I am going to write one page.

I would work on it do 30 minutes and then break for five. Then I would work on it for 20 minutes and break for 10. After that, I will work for 10 minutes and break for 20. Then I will go back to working for 30 minutes and continue the cycle.