Passage Summary: A person argues that doctors shouldn't stop giving health advice just because the main goal, like losing weight, isn't always achieved, since the advice still helps in other ways.

Conclusion: Doctors should continue to recommend changes in diet and exercise even if those changes rarely lead to weight loss.

Reasoning: Diet and exercise provide health benefits that are independent of whether or not a person loses weight.

Analysis: The argument hinges on the idea that an action's value isn't solely determined by its primary or most visible goal. To find a matching principle, look for a scenario where a practice is defended because it offers secondary benefits, even when it fails to produce its most intended result. This logic is common in human behavior—we often keep doing things for the 'side effects' even when the main prize remains elusive.