This is why, in a 9-5 job, it can be next to impossible to pursue other interests and develop oneself. It’s hard enough to be “on top” of things in the evenings, let alone super-concentrate on any productivity:

Grad school is a marathon not a sprint, and one of the big reasons people burn out in grad school is that they apply 20-something strategies of brute-force [instead of] slow but steady, 30-something tactics that get you through…

…you are at your most productive after you wake up, and that you’ve basically got about 4-5 hours of genuine, hard-core concentration in you per day — what I call ‘being on the bottom of things’: the ability to ignore the world and just drill down to super-concentration level. When that’s done, it’s done.

That’s why you spend the rest of the day keeping ‘on top’ of things — browsing, scanning, surfing, paying the bills, spell-checking, going to lectures, and otherwise getting ready to dive down back to the bottom.