The problem: There is not only spam information - there are also spam thoughts.
Spam is reducing our productivity and happiness. But there is not only spam mail and spam information - there are also spam thoughts.
The reason: We want to note everything down because our brain tends to forget.
We want to improve and learn from our experiences. Going to work in the morning offers a lot of impressions that triggers thoughts as every impression (as well as information) contains potential issues to learn. GTD tells us to write down everything - although there are also some critics on this.
The solution: Trust your brain and let go.
While on the go or while working on something else there are thoughts coming only loosely related to the topic of your focus. If it is important it will return, come back in the same or similar way on other opportunities. If the same thought returns more often then it is worth more being noted down and reviewed. Don't act immediately on a single thought or let a single thought be the reason for (big) decisions.
Related posts: Information overflow, Who cares?, All Done status, Crying for attention, Analysis and therapy.