Being an entrepreneur, I've really had an exhilarating ride until now. And I don't expect that to end any time soon...
I do however agree with Eric full-heartedly when he says that entrepreneurship isn't quite as glamourous as it is sometimes made out to be. Heck, most days at the office are a tough slog, instead of a comfortable cruise. Having to make tough decisions daily requires a kind of focus and energy that is tedious, meticulous and not just adrenaline-driven.
True entrepreneurs will find the "fun" in these tasks at hand and for those pure souls, the entrepreneurial rollercoaster will always be exhilarating. But to deny that it requires a bucket load of tedious inputs would be ignorance of the highest degree.