there are certification organizations that hold 2 or 3 days events at the end of which you take a test and – voila – are a personal trainer. Even though they usually provide you with a book in advance, the set up is such that you will pass the test.
While that is a way to get certified, it probably won’t make you a stellar personal trainer. There is no way getting around studying, and while book learning without practical experience is not the answer either it is an important part of the picture.
Much depends on your own personal starting point. Probably one of the greatest challenges is not to use our own personal experience with exercise to extrapolate on others, but to look at another exerciser from THEIR starting point.