To think big is to excite everyone including yourself with a bold idea, one that captures the imagination and causes the heart to beat a little faster.
But for most people that bold idea then dies because they say to themselves and others, "But I don't have the money to do this. And it's too risky." In other words they're defeated before they start.
Instead, take small steps to get your idea off the ground. The Wright Brothers took time to build and test flying devices before they launched anything that looked like the first airplane in 1903.
Walmart was a bold idea in 1962 but it started with just one store, even after others had already developed discount retailing before Sam Walton did.
In the 1970s Steve Jobs and Steve Wozniak had a great concept in Apple Computer but its initial customers were a handful of computer enthusiasts.
If you have a bold idea, think big but start small and the next thing you know your idea just might change the world.