No Reason is a Good Reason not to put effort into something

 

The default position in life is to be curious. When someone asks you "why not" you can respond with "because I don't have a reason to" as this implies the way humans work, we don't do something without a value reason to pursue something.

Similarly, if a cop asks you why you don't want to open your trunk for an investigation assuming you have nothing you hide is an example of not having a reason to pursue anything else, as that is not how we formulate goals.