Bestselling author James Patterson's first book published 47 years ago — and his hustle hasn't stopped since then.

With more than 400 million copies of his books sold to date, Patterson routinely tops highest-paid author lists — and at age 75, he's currently working on 31 new projects simultaneously, he recently told GQ.

His secret: A consistent seven-day work routine starting around 5 a.m. and ending at 6 p.m. After working for the first hour, Patterson takes an hourlong break to hit balls at a local golf course before returning to his desk to work — mostly continuously — from 8 a.m. to 6 p.m.

"I do what I do seven days a week," Patterson said, adding: "I'll take a couple breaks if I need them, which I usually do. Obviously, what that [day] results in is more books than my publisher wants."

Those breaks are crucial. Research shows spending more time resting during the workday can stimulate creativity, while improving concentration and efficiency. 

Often, Patterson spends his breaks chatting with his wife Sue, he said. Those types of respites are especially helpful: A 75-year Harvard study on happiness found investing in relationships is the single most important change people can make to improve happiness.

Having a reliable morning routine also boosts productivity and overall wellness: Research shows that it can reduce stress, improve work productivity and boost your energy levels.

Still, choosing to work 77 hours per week is uncommon, especially at age 75. Patterson pointed to a piece of guiding advice from his grandmother that helps illuminate the drive behind his work ethic.

"[She] said, 'Hungry dogs run faster,'" Patterson said. "I've always been a hungry dog."

Collaboration helps, too. Most of Patterson's recent works have been co-written with a variety of other authors, and Patterson typically segments his day into time spent developing new ideas, writing and reading passages written by his collaborators, he said.

Typically, Patterson writes an initial 50- to 70-page outline for a story before encouraging his co-writers to start filling in the gaps with sentences, paragraphs and chapters, he said.

His ideas come from a thick folder he keeps, with each page holding up to 10 or 11 fragments of concepts, he added. When Patterson looks for inspiration, the scribblings — some of which have been there "for a long time," he said — provide a ready-made source.

As for the writing itself, Patterson writes longhand, with an assistant transcribing his handwriting into typed drafts, he said. He further edits those typed drafts by hand, only focusing on what he's changed since the last version.

Science backs up Patterson's affinity for writing longhand: People retain handwritten information more effectively than typed notes, studies show.

Patterson doesn't plan to stop anytime soon. "I have no interest in retiring," he said. "You don't retire from play. Why would you? I will stop doing it when I feel I can't do it."

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