If this was true, you could lay back relaxed and watch where your brain takes you. But we experience life as a never ending stream of choices, usually between what's easy and what's right, and pursuing the right choice takes a constant effort. We are presented with problems and have to figure out solutions on our own, with no guarantees of success.

This "I'm just an observer" idea may be true at some higher level, if you're a monk on the threshold of nirvana, but for common folk this mindset leads nowhere.