Why are therapy and medication together the best treatment?

I know this question may be obvious, but can you tell me how your experience with taking medication while seeking therapy treatment helped you? How do they work together?

In part, I'm asking this because I'm in therapy now following a nervous breakdown (panic/anxiety mostly, but depression too). I have been hesitant to take an antidepressant for fear that it'll diminish my emotions, however it's also taking a long time to recover from this breakdown mentally and physically.