Before the $6.4 billion deal to sell his AI devices startup io to Sam Altman's OpenAI, industrial designer Jony Ive spent more than 10 years working closely with Apple co-founder Steve Jobs to create products like the iPhone, iPad and MacBook.

Working with a boss as famously demanding as Jobs wasn't easy, but it was rewarding, Ive said at a Vanity Fair event in 2014. He learned a simple-yet-important life lesson from Jobs, whom he called "the most remarkably focused person I've ever met in my life."

"You can achieve so much when you truly focus," Ive said Jobs taught him, adding that "it still shocks me how few people actually practice this." He defined true focus as a constant effort, during "every minute" of every waking moment, rather than an internal switch you flip on and off.

"You don't decide on Monday, 'You know what? I'm going to be focused,'" Ive said.

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True focus comes from sacrifice, added Ive, explaining that Jobs frequently presented him with a question: "How many things have you said no to?" Ive would respond with ideas and opportunities that he'd turned down, but "wasn't vaguely interested in doing those things anyway, so there was no real sacrifice."

Eventually, Ive learned that what Jobs was asking about something deeper than the prioritization of his obligations. "What focus means is saying 'no' to something that you, with every bone in your body, think is a phenomenal idea, and you wake up thinking about it, but you say no to it because you're focusing on something else," he said.

Deep focus is difficult to achieve, but you can improve your focus skills by setting aside an hour or two each day to enter a flow state — where you become so immersed in your activity that you lose track of time, happiness coach Jessica Weiss told CNBC Make It in November.

Weiss recommended selecting a task "that's slightly more difficult than something you would ordinarily do," which will "slightly push you out of your comfort zone." With your task set, put away anything that might distract you — find a room with a door, turn your phone off — and let yourself sink into your work.

Seeing what you can accomplish in those one or two hours will bring you a sense of satisfaction, and will make it a little bit easier to focus next time, said Weiss.

"It'll kind of remind you of your ability to concentrate," she said. "Which I think is what we all need in those moments when we're like, 'Oh my God, I can't focus.'"

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