My biggest piece of advice, that resulted in my biggest push of productivity, was a daily routine tailored to how your performance varies over the day.

For me

(1) sitting down and writing (anything: paper, thesis, proposal, blog) first thing in the morning, before emails. You want the habit of writing, and feeling weird if you don’t. This is my peak performance for the day, the hardest thing for me.

(2) celebrate your writing with a nice coffee and find a nice place on campus to study a paper. My 2nd most demanding task.

(3) Lunchbreak with colleagues. Socialize, discuss ideas but also just fun.

(4) My low point after lunch, I’ll try to have meetings here or do some routine stuff (forms, reimbursement, news, internet).

(5) Exploratory research, programming, planning, ideation, discussions, brainstorming.

(6) Exercise, sport.

(7) Later in the day my programming would come back strongest towards the evening.

(8) If you have family, go see them and have dinner with them. If not, I’d get another coffee and see how far I can go.

EDIT: (9) Write the todo list for the next day and open the document you want to work on the next morning. You don’t want to waste any brain cycles in the morning deciding what to work on.

Of course this is different for everyone, but matching your productivity to the task will make it a habit and much more effective.