Lol, when you say “data entry” you make it sound so boring. 
The reward comes from checking something off. 
So you wouldn’t like my system for reading difficult textbooks, then - I write each page number on a separate line and cross it off once I’ve read that page.
My system for my project 240 is similar - every time I complete a 15-min time block I check it off multiple places: my paper journal, a separate piece of paper, and on Beeminder.
I’m pretty ADD so the extra dopamine from all that checking things off really helps.