Chris Hadfield had a goal that wasn't just hard to reach. It was impossible.

The Canadian wanted to become an astronaut. There was only one hitch: Canada didn't have a space agency. That was in the summer of 1969. Today, people know Chris Hadfield as the guy who sang "Space Oddity" from the International Space Station and gave a popular TED Talk.

Hadfield is now sharing career advice on MasterClass that applies to anyone who wants to start a business or who has a dream that seems a distant, if not impossible, goal. His four-step process particularly resonated with me:

1. Give yourself permission to dream.

When Hadfield was born, no one had ever flown to space. When Neil Armstrong was born, the word astronaut hadn't been invented. "What I learned from Apollo 11 was that things change and that impossible things happen. That's a really important lesson to learn no matter what stage of life you're in," Hadfield says.

I agree. After I left a six-figure job to start my own practice and write books, many people told me that book deals from major publishers are nearly impossible. But as long as I knew one person had done it, I gave myself permission to believe that it could be done. Nine books later, I'm glad I took the opportunity to dream bigger.

Be patient and start working on who you want to be, even if your goal seems like a long shot.

2. Make sure you're really passionate about your dream.

Hadfield wasn't sure that he wanted to take the long, arduous road to pursuing his dream after graduating from high school. He took six months off to travel around Europe. The perspective he gained helped him rediscover his passion.

When I meet entrepreneurs or small-business owners, I ask why they started their company or entered the field. If they can't stop talking about how much they love what they do, I know they might have a chance to be successful. If you're not interested in the subject, it'll show--and you won't have the energy to pursue the hard road ahead. 

3. Pursue a game plan and celebrate milestones.

Once Hadfield had decided to pursue his passion, he made a game plan. To be an astronaut, he'd have to attend university, study mechanical engineering, get a master's degree, and become a pilot.

Hadfield joined the Air Force at the age of 18, knowing the odds of becoming an astronaut "were terrible." But since he loved the subject, he figured that he'd learn something every step of the way--and that he'd become a better person with every milestone.

In his early 30s, Hadfield had two degrees and was defending North America as a fighter pilot. When the Canadian Space Agency was formed in 1989, a call went out: Does anyone want to be an astronaut?

This is the most critical step in the journey. If you don't have a fixed goal in mind for where you want to be one year from now, or five or 10, then you'll squander your time. If your dream is to open a restaurant but it seems like an impossible goal, take a small step this weekend. Read a book by a famous chef or restaurateur (like Danny Meyer's Setting the Table). Take an online class or make plans to attend customer service training at the Disney Institute or another hospitality-based course.

According to Hadfield, "It's hard to choose what to do next if you don't know where you're trying to get to."

4. Don't trumpet your goals.

What young boy doesn't want to be an astronaut? If Hadfield had shared his dream with a lot of people, the feedback would have been demoralizing. "The most important step is the one you make inside your own head," says Hadfield. "Don't trumpet it out loud. Don't evaluate your dream on the basis of other people's reactions."

Don't wait for external validation before you pursue your goals. Most people don't share your passion or dreams. Focus privately on the accomplishments that you need to reach your dream. Give yourself the pleasure and satisfaction of knowing you're getting one step closer to becoming the person you dream of.

Hadfield's original goal was to walk on the moon by the age of 45. He's nearing 60 and hasn't done it yet. But it doesn't mean he has failed. He has a master's degree, three children, has walked in space, and accomplished things he thought he'd never do. "You don't have to wait until the end to feel good about all the parts in the middle," he says.

What's your dream goal? If it seems impossible, it just might be worth pursuing.