In my case, it was due to crunch time shortly before release, and then after the project was released falling into a void of not knowing how to fill my time. W

In my case, it was due to crunch time shortly before release, and then after the project was released falling into a void of not knowing how to fill my time. Which caused stress and eventually a burnout that I am only just slowly getting out of, after about 5 months. I suppose it is different for each person though.