The biggest improvement in my work performance followed significant improvements in how I sleep, eat, and exercise. No app, trick, or life hack has ever come close to the sheer magnitude of how much more mental power and focus I can wield. None of the improvements happened overnight, and they usually happened in parallel because they’re closely related. If you sleep better, it’ll be easier to make better food choices; if you eat better, you’ll fuel and prepare your body for exercise; if you exercise, you’ll feel good after it, keep your body (brain) healthy, and you’ll sleep better.
I was reasonably successful in keeping all three in check, so I incorrectly thought that marginally improving them wouldn’t make much difference. I was wrong. Due to having two small kids and a demanding job, there are always periods in a year where I can’t maintain my healthy routine. During those periods, I consistently observe that I perform tasks longer and the output is not up to my standards. For example, a task—for which I would routinely need an hour—takes an hour and a half, and I have to revise it the next day.
If I’m honest with myself, this is all boring advice, probably along the lines of what your parents or grandparents would tell you. But sometimes boring works.