Success is dependent upon the glands - sweat glands.

Ziglar’s quip turns “success” into a bodily metaphor: it depends less on innate gifts or luck than on exertion—work that makes you sweat. The joke hinges on the word “glands,” playfully rejecting pseudo-scientific explanations (or excuses) in favor of a plain ethic of effort. In Ziglar’s broader motivational worldview, the line reinforces personal responsibility: consistent discipline, preparation, and persistence are the practical drivers of achievement. The humor makes the message memorable while also deflating the tendency to overcomplicate success with theories, instead pointing to the unglamorous, physical reality of sustained labor.