What sets highly successful people like Elon Musk, Oprah Winfrey, and Mark Zuckerberg apart from the rest of us? One man interviewed hundreds of self-made millionaires to find out. Tom Corley, an accountant and financial planner, surveyed 233 wealthy individuals, mostly self-made millionaires, on their daily habits. He compared those answers to responses from 128 poorer individuals, or those with less than $35,000 in annual gross income.

In his best-selling book Change Your Habits, Change Your Life, Corley explains that wealthy people set themselves up for success in a few specific ways. Here are the habits they have in common.

1. Reading

A whopping 88 percent of rich people in Corley's research say they devote thirty minutes or more each day to education or self-improvement through reading.

Most do not read for entertainment; they prefer biographies, history, and self-help books. If you enjoy a good novel, that can help you too. Science shows that reading for pleasure can also boost your career. And Corley's point holds for many kinds of narratives. "There are important life lessons to be learned in biographies of people with rags-to-riches stories," he writes. "Biographies expose the thinking habits, challenges, and ups-and-downs of the subject."

2. Exercise

Working out regularly clears your head and makes you feel more motivated, studies show.

According to Corley, 76 percent of the rich carve out 30 minutes or more for aerobic exercise like jogging, biking, or walking each day.

3. Building positive relationships

"You are only as successful as those you frequently associate with," Corley says.

If you don't have highly-motivated people in your personal network yet, fear not. Self-made millionaires volunteer, which is a great way to meet other positive, motivated individuals. You could also join groups for people who share your same career or personal interests, Corley suggests. Then develop the relationship by keeping in touch. And be choosy about who you spend your time with. "[Successful people] also make a point to limit their exposure to toxic, negative people," says Corley.

4. Pursuing goals

Most self-made millionaires don't end up rich accidentally, Corley's research finds. They make plans.

Eighty percent of the wealthy are "obsessed with pursuing goals," he writes. They refer to both daily and long-term goals regularly. "I'm here to tell you to avoid putting your ladder on someone else's wall and then spending the best years of your life climbing it," Corley says. "Find your own wall, your own dreams, and your own goals, and pursue them."

5. Sleeping well

Albert Einstein reportedly preferred to get at least 10 hours of sleep a night. If you too function best well-rested, Corley has some good news.

An overwhelming 89 percent of self made millionaire sleep seven or eight hours each night, or more. "Sleep is critical to success," he writes, citing its effects on memory function and creative thinking.

6. Developing multiple incomes

"Self-made millionaires do not rely on one singular source of income," Corley says. "They develop multiple streams."

So how many sources of income do they have? "Sixty-five percent had at least three streams of income that they created prior to making their first million dollars," Corley says. Having a side-business or income generating investments like REITs or real estate are a few common additional sources of income. "Diversifying sources of income allows you to weather the economic downturns that inevitably occur," he writes.

7. Avoiding wastes of time