In the spirit of the Dove Campaign for Real Beauty, here's another interesting video that shows the dramatic effect of post-processing, underscoring the disconnect between natural beauty and the constructed image.
While I manipulate tones, color and contrast, the extent of photo manipulation beyond that is to remove blemishes and stray hairs. It's much easier to make adjustments to lighting or to shoot from a different angle than to spend a lot of time in post-production; I enjoy shooting more than editing, so I focus on time with the person I'm photographing instead of Photoshop.