The PayPal founder, who now runs space-exploration firm SpaceX and electric car company Tesla Motors, explains how to send a start-up stratospheric and outlines his own Mars mission...

Think about what will most affect the future of humanity.

That's the thread that unites everything I'm working on. When I was at university, the three areas I came up with were sustainable energy, the internet and space exploration. As a result of the financial success of PayPal, I had the capital to set up SpaceX and Tesla, but I never actually thought that I would be able to participate in all three areas.

Speed is so important for a startup.

I almost missed the creation of the internet. It was 1995, and I thought, "I can either start my PhD at Stanford, or I can defer for a while and see if I can set up a company." I was concerned that if I just did graduate studies, I'd watch the creation of the internet and I wouldn't be able to stand not being a part of that. So my brother and I created Zip2, a piece of software to help bring media companies online. We sold it a few years later and then went on to set up PayPal.

You have to think big.

What I'm doing at SpaceX is in a different league to people like Richard Branson and [Amazon founder and Blue Origin pioneer] Jeff Bezos. Our vehicles have around 100 times more energy than Richard Branson's. What he's doing is great - in fact, I've bought a ticket! But there is a pretty big distinction: what he's doing will be a really fun joyride, but there's no path to making life multi-planetary, which is our goal. We want to put life on Mars.

Determination is key.

I knew there was a good chance I'd fail with Tesla, but I never lost my resolve. The recession was disproportionately difficult for the car business; Tesla was raising a big financing round at the end of 2008 when the economy collapsed, and I had to commit every penny I had to the company to make it through. I gave it everything and, fortunately, it was just enough.

You need to stay in close range of your product in the first few years.

At the beginning, I hired a CEO to run Tesla, but it became apparent that he simply couldn't get the job done. Taking over was the only option I had. Now I have a great team, and most of my time is spent in engineering and design. That's my forte.

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None of this would have been possible if I hadn't been living in California.

There's no better place in the world for technology start-ups than Silicon Valley; there's such an incredible well of talent and capital and resources. The whole system is set up to foster the creation of new companies.

We need to introduce people to electric cars, not expect them to come to us.

The problem with car dealerships is you've already decided what you want to buy before you even go there, and you're really just going there to talk through some annoying negotiation. So we're opening our stores in high-end, high-traffic shopping centres and streets where people are walking by and want to come in and ask questions. That gives us enough time to talk to them about electric cars.

I think we'll see a dramatic shift towards electric cars over the next 20 years, maybe even ten.

Petrol will get more and more expensive over time, so even if there weren't environmental issues, humanity would face economic collapse if we didn't find a way towards sustainable motor transport. And we're taking a big risk in terms of how many trillions of tonnes of CO2 we can put into the atmosphere before things go seriously wrong. Why run that experiment?

Don't take yourself too seriously, or you'll start believing your own bulls***.

On one of the SpaceX flights we had a secret payload: a wheel of cheese. We flew to orbit and brought it back, so it was the world's first "space cheese"; it was, in part, a tribute to Monty Python.

As told to Luciana Bellini