I truly believe that this quote is at the core of life and more specifically, our experience of life. How we view the world, our beliefs and the actions we consequently take, determine our happiness and contentment.
You are very lucky. You have a most powerful tool at your disposal. Your mind. It has no boundaries. It can take you anywhere you want to go and lead you to happiness and contentment whenever you wish.
Every man-made object that you see around you, every business or service you can purchase, began as an idea in someones mind. The way that you act and behave, the things that you do every day are driven by your mind, whether unconsciously (blinking, breathing) or consciously (what will I do today?).
It's a rather philosophical thing to get your head around, but if you can understand that "you" are not your mind but that you are actually in control of your thinking, life can be a lot more fun!
Why is it that one person is afraid of heights and won't leave terra firma whilst another will happily jump out of a plane and skydive for fun?
I'm not suggesting for a second that sky diving is for everyone! but just consider this: it is simply a difference in thought processes that differentiates the two people.
The good news is that if you have goals and wish to change your life, you can do this simply by working on your mind. Challenge your limiting beliefs. Ask yourself: "Is that really true?". Don't find excuses for why you can't do something, ask yourself: "Why Not"?. Who is that voice in you head that says you can't? You can! You want to be more confident? Successful? Happy? Choose it. Stop your negative thoughts dead in their tracks and reverse them. "I could never start my own business" becomes " I can start my own business". "I'm too old to start a new hobby" becomes "I'll never be too old to start a new hobby"...
There is much literature on this subject. One site I have found very useful is The Work of Byron Katie
It's free and you can access the link here.