My biggest motivation? Just to keep challenging myself

There isn't a flight goes by when I don't stare out of the window and thank my stars for what I'm seeing and feeling.

I've been in Africa, and I've been to hospitals of Africa, and they're not hospitals, they're places where people go to die. And rows and rows and rows of people just dying and the waiting rooms of the hospitals are full of people waiting to get into the beds of the people who died the night before, and they're dying from unnecessary diseases.

Those people who spend their time working on things they love are usually the ones enjoying life the most. They are also the ones who dared to take a risk and chase their dreams.

We'll not be sending anyone into space before it is safe and the vehicle is well and truly tested.

Every risk is worth taking as long as it's for a good cause, and contributes to a good life.

All successful people - not just entrepreneurs - have got things wrong over and over again before finding the right solution.