"We are not the things we say we will do," says American writer Amy Dickinson. "Instead, we are the things that we actually do, over and over again."

Routine is a foundation for long-term success. It creates structure and healthy habits, and will keep you going on days when you're feeling less motivated. What's more, a good routine is directly linked to higher output.

In other words, sticking to a routine equals more things getting done. This is why many high achievers are sticklers for scheduling every hour of the day. To discover how the very best in the world do it, OnDeck, the small-business loan provider, decided to investigate the habits and routines of the world's most successful business leaders.

Here's a look at how three billionaires plan their days.

Jack Dorsey, CEO of Twitter

Jack Dorsey wakes up at 5 every morning. He dedicates the first few hours of his day to "personal care," which includes a 60-minute meditation, a 6-mile jog, and an ice bath to shock his system into action.

According to the OnDeck study, Dorsey believes his rigorous morning routine gives him the mental confidence to tackle any challenges that come up during the day. And there's some hard science to back up the theory. Research by Stanford psychologist Kelly McGonigal suggests that forcing ourselves to do uncomfortable things builds up neural pathways associated with mental resilience.

In other words, mental toughness is something we can learn and cultivate. We just need to put in the work and embrace the struggle. And Dorsey is no stranger to either concept. His intense mornings are just a warm-up for an 11-hour workday that doesn't end until after midnight. 

Elon Musk, CEO of Tesla Motors

Elon Musk struggles to find enough time for actual sleep. But, then again, he's reinventing the automobile industry, building high-speed underground transport networks across the U.S., and regularly sending rockets into orbit. So you won't be surprised to hear that Musk works 16 hours a day, including weekends.

OnDeck's analysis finds that Musk designs his daily routine with the kind of precision you'd expect from a bona fide rocket scientist. From 7 a.m. to 12 noon, Musk is busy with emails, phone calls, and strategy sessions with his management team. A working lunch is followed by a walk around the factory floor. The evening hours between 6 p.m. to 9 p.m. are family time. Then it's more emails and meetings. Finally, Musk clocks off around 1 a.m., grabbing six hours of sleep before waking up and doing it all over again!

Mark Cuban, billionaire investor, Shark Tank star

Billionaire tech investor and Shark Tank star Mark Cuban is another highly successful business leader who believes that less is often more. OnDeck documents that Cuban spends just six hours a day managing his $4 billion fortune -- but it's an intense six hours.

Cuban rises around 5:30 a.m. and always hits the ground running. "Business is my morning meditation," says Cuban. "I get up and I work immediately. I love doing this." He doesn't stop until midday and always takes an hour in the evening to plan out his next set of goals. Because as far as Cuban is concerned, business is all about results. "Don't get caught up in how many hours you work," advises Cuban. "Judge success based on having goals and measuring your results. Hard work, and lots of it, is certainly needed, but focus on what you can actually get done."

Success isn't accidental, it's something you plan for. Everyone's plan will look a little different, so don't worry about keeping up with billionaires waking up before the crack of dawn. The most important thing is creating a daily routine that enables you to be the best version of yourself. Then stick to it. Because that's how you turn winning into a habit.