I am probably terribly wrong in my approach, but I treat DS's anxieties as if they were possible/realistic/etc and ask, well, what do we do about that? Car sickness - okay, let's pack some sick bags, and some anti-nausea gum and is there anything else you want? A change of clothes? Let's be prepared!
I try and treat his anxieties as simply obstacles to overcome. Honestly, most of the stuff he's anxious about IS possible, though not always likely, so we discuss what would happen if his fears came true. What if that rope broke and I fell when I was climbing? Well, there's a padded mat, and if I fell funny, they'd call the awesome paramedics and they'd take me to the ER and fix me right up! You know your friend so-and-so who broke an arm, right? He wasn't rolling around crying at school was he? Nope, he was fine because doctors are awesome!
That sort of thing. It's worked pretty well so far. I do tend to have to "shiny" things up (ie, paramedics came come super fast and doctors can always fix things, etc) and we'll probably have to alter this later, but for now I focus on getting through each day!
