World renowned scientist Stephen Hawking recently passed away at the age of 76, but he left behind an amazing legacy and many great quotes that we can all learn from and live by.

Hawking is a personal inspiration for me because of the obstacles he had to overcome to live such an extraordinary life.

I have imagined how hard it must have been to do what he did by talking one letter at a time and I have realized that he is the ultimate problem solver. He was faced with overwhelming challenges and he overcame them to communicate his vision to the world.

As entrepreneurs, we are also problem solvers. Although most of us will never know the challenges that Hawking had to overcome, we can nevertheless learn from him in our capacity as world changers.

I've gathered some of the best Hawking quotes here and have reflected on the lessons they hold for us as entrepreneurs.

1. Always be grateful.

"My expectations were reduced to zero when I was 21. Everything since then has been a bonus" This quote comes from an interview published in The New York Times in December 2004.

Hawking had motor neurone disease, which basically caused his body to stop working over his lifetime. However, the best-selling author and physicist carried on, having a hugely successful life after he was diagnosed and the disease caused him to completely lose the ability to speak or move.

There is no hardship you cannot overcome and even in the darkest days, we should all be grateful for what we do have. I've lived through my fair share of business failures, but I've always been thankful for my family and my good health.

2. Imperfection leads to opportunity.

"Without imperfection, you or I would not exist" - This is from the television special "Into The Universe With Stephen Hawking," which aired on The Discovery Channel in 2010.

If the world was perfect, there would be no problems to solve. We should never lament the struggles we experience in this world because it's those struggles that spawn business ideas. Our role as entrepreneurs is to try and make the world a better place and bring it just a little bit closer to perfection. It's in the imperfection of the world that you will find a problem to solve and an idea for a business.

The main business that my wife and I run sells drug testing equipment to other businesses. I would definitely call drug abuse an imperfection in the world, but this unfortunate problem has given us an opportunity to try and improve the world by making workplaces safer.

3. Never give up.

"Remember to look up at the stars and not down at your feet.Try to make sense of what you see and wonder about what makes the universe exist. However difficult life may seem there is always something you can do and succeed at. It matters that you don't just give up." Unfortunately, I could not identify the source of this Hawking quote, but it is commonly attributed to him.

Perhaps more than anyone, Hawking could speak with authority on not giving up. To say his life was difficult is an understatement, but he lived a fruitful life.

You will find that things get tough and entrepreneurialism is difficult and stressful, but don't give up because giving up is the easy way out. You may go through a few different businesses, but if you keep honing your skills, you will find one that works for you.

I myself tried several different businesses before finding one that was successful. I shudder to think what my life would be like had I just given up after my first business that didn't work out.

4. Always keep your sense of humor.

"Life would be tragic if it weren't funny." This is from an interview in The New York Times in December 2004.

Hawking was as famous for his wit as his theories about the universe. Hardships befall everyone and surely some of them are tragic, but life is much easier to handle -- both the good and bad -- if you do so with a sense of humor.

I cherish the times I get to laugh even when business is difficult. Fortunately, my wife and I have an amazing staff and we all get along well. It makes the rough times more palatable and it makes the good times even better. There's always something to smile about.

He may be gone, but the legacy and wisdom of Stephen Hawking will live on for a long time. His was a life full of lessons that we can all learn from.