Here we go = Now we start

It's typically an expression said by someone who's about to do something that requires skill/courage etc... For example, "Here we go," he murmured grimly, as he sat behind the wheel of the car for the first time. Or if you're on a roller coaster and it's about to start, you might turn to your friend and say, "Here we go!" Did that make sense? xD

Thanks :3

A quote brought from here: http://books.google.ca/books?id=wuLrTJ0wtlMC&pg=PA217&lpg=PA217&dq=%22here+we+go%22&source=bl&ots=cwDemYFb6K&sig=YvAy_mSmFnKsDrXUwajWnqSlkYM&hl=en&sa=X&ei=zWZWUOPjLOGyyAGZj4C4BA&redir_esc=y#v=onepage&q=%22here%20we%20go%22&f=false "Said by a person ready to begin something that takes skill, luck or courage "

Its like ( here we start )