The eight-hour workday started its life as a socialist dream. The Welsh textile mill owner and social reformer Robert Owen is credited as the first person to articulate it, by calling for “eight hours labor, eight hours recreation, and eight hours rest” for workers in the early 19th century. This was much better than the 12- or 14-hour days factory workers, including children, were expected to put in at the time. Over the next 100 years or so, labor unions in the US pushed for and won adoption of the eight-hour standard in various industries. Henry Ford brought the idea further into the mainstream in 1926 by mandating a five-day, 40-hour workweek in his company’s factories. In 1940, Congress officially set the American workweek at 40 hours.

There’s just one problem in 2019: It’s all but impossible to actually work for eight hours a day in the jobs so many of us now have. Like most people writing hot takes and think pieces about productivity, I’m focusing on knowledge workers here—those of us who work at desks, mostly in front of computers, in offices or from home. Especially those of us who spend those hours making things, like writers, coders, and graphic designers. (Honestly, I think eight hours a day is too long to work in a factory, a restaurant, a call center, or a store too, and we should rethink and relegislate this standard in all industries.)

I’m a full-time freelance writer who works from home, so I’m responsible for setting my own schedule. This is great, and also terrible. Like many knowledge workers, I reach the end of many workdays thinking, Where did all those hours go? What did I actually do today? And unlike people who go to an office, I can’t say Oh, I went to the office! I don’t have an external measure of productivity to judge myself against, aside from the culturally ingrained idea that if I’m a “full-time” writer, I should be working for eight hours a day, five days a week.

To figure out where my hours were going, and if I was meeting this arbitrary metric designed for criminally exploited 19th-century factory workers, I installed RescueTime. This is essentially spyware I use on myself. It tracks everything I do on my computer and shows me how long I spend working each day, and what I actually do during that time. It’s creepy, and I love it.

I recently had an exceptionally busy and stressful week of work, as I was finishing a long magazine feature and writing a quick-turnaround science news story about a technical topic. Trying to do both those things at the same time was definitely too much work. I know this because I felt awful—depressed, anxious, eating poorly, and not exercising enough—during this push, and because I got sick immediately after it was over.

When I looked at my RescueTime stats from those days (a Wednesday to a Monday; freelance schedules are weird), it turned out I had worked a total of 35 hours and 17 minutes. I didn’t take much of a weekend, working two hours on Saturday and over seven hours on Sunday. My productivity was high at an average of 84 percent, but not particularly unusual according to my RescueTime weekly reports. (I’m delighted to brag that I usually spend less than 30 minutes a day on Twitter, something I never would have guessed before installing RescueTime and that continues to shock me. I thought it was eating my days. But no, that’s email—another post for another time.)