If you were looking to find a new apartment, but you didn’t have a lot of spare time, you would probably hire a real estate broker to help you. The broker would listen to what you wanted in a dwelling, do the leg work for you and arrange for a time when you could meet with him so that he could show you the apartments he found that fit your needs.
A personal trainer can do the same thing for you with exercise. A good trainer will assess your needs, listen to your concerns, and do the leg work for you (not literally of course–you still need to do those lunges yourself!).
Having a trainer select safe, effective exercises for you can save you the hassle of a lot of trial and error. The same way that a good real estate broker knows the neighborhood and knows of the best deals without having to look at a million places, a good trainer knows how to give you a challenging and effective workout without wasting a lot of time.
Just like that real estate agent will ideally save you both time AND money in the big picture (time is money after all, right?), having a personal trainer can be a valuable investment in your health. So if your time is valuable, then it’s worth your while to work out with a qualified personal trainer.
However, if you do have the time and inclination to explore for yourself, I encourage you to do so. There is something to be said about having first hand knowledge which can only come from real life trial and error. There is no substitute for experience, and experience only comes with time. Remember, every fitness fanatic or personal trainer had to start somewhere–just like you. Perhaps in time you’ll wind up becoming the broker yourself.