A coworker and me did together a "hackathon by choice" this week to finish a project. We did it only because we thought it would be cool and be able to finish the thing. Well it was surprisingly fun to stay awake 36 hours, coding all through, having a good flow. After that, our boss came and was very proud of our work and he was able to send it for inspection to the client. I stayed a bit longer to fix a few minor bugs, but after 42h I was finally in bed. 😁
Our boss gives us the following Monday off.
But I think on other projects, often deadlines take the fun out of it, if they are not estimated well... I mean you do great, high-professional work but in the end you feel bad, useless, slow and incompetent because of the pressure.