Diet Pills I just don't know...

I am soooo tired of being fat. Of course I'm older so it makes it even harder to lose weight. I have hesitated in the past to use diet pills. I mean will they work? Do you have to take them forever? Are they good for you? I have been searching online for healthy diet pills made out of natural ingredients, but I am sensitive to a lot of different herbs so I'm not sure what I can or can't take. The only way I guess is trial and error. Anyone have any suggestions??