Picture an old Library card catalog or say, a Safety Deposit box array in a bank vault. They get labelled and you keep filing the associated input into those areas. The room technique is another as you describe. Picture a house with various rooms and begin associated / grouping the item / topics / issues into respective rooms.
Examples:
Annoying neighbors - the outside garbage can
Abuse - in the garbage disposal unit.
Health Concerns you can't control - picture it as the tools / steps to help mitigate
Another technique (depending on what you are seeking to accomplish) is to first recognize the nature of the external input(s) for the systems (spheres) within which they function and in turn re-prioritize them or sublimate them.
For example, if it is constant bad news / sky is falling / earth is coming to an end news media, shut it off, or limit it to things that are more relevant. For example, the news media is driven by ratings and ratings are gained by being as sensational and attention grabbing as possible. Also, once you start viewing the flow of inputs as what someone (program director/ corporate entity) wants to you to see, hear, etc... it makes it easier to say, OK, I am going to file that
or limit it altogether and pursue other systems for news and information that have less of an emphasis on making me into a manipulable instrument of consumption and fear.
If it is say, family / friends making stupid comments limit the contact points and the atmosphere within which you do have contact. Become knowledgeable on how these systems work to reorient some of their "white noise" internally and introspectively to realize the same, that many of the external stimuli to them are for someone else's idea of what they want or how they want you to react. I.E. It's called programming for a reason. It is what someone else deems worthy of covering.
If there is a co-worker person you see you are overly attracted to sexually and you shouldn't be based on your status or relation to them in said environment. Picture them as some status to remove the allure. For example, if you're male and the female in office makes you get all hot and bothered, start imagining her as your sister or your mother at that age and how you would react and behave.
If it is something that tends to make you get overly emotional, say a political issue, picture the topic first as a container and that only when you are in the room with that container can you emote. If you can't get into the location mentally you can't be bothered by it. An example of this would be when you observe people who are easily triggered by flashpoint issues. Don't become one of them. Picture the flashpoint issue (trigger) as being someplace else so you do not over react to it.
Another would be personal insults or degrading comments (depending on the situation and environment) picture the comments as water and yourself as say a duck and the comments roll off of you like water on a ducks back.
It won't happen overnight, I think each individual depending on how they were raised / acculturated to the society and environment in which they live, may already do so to various degrees. You will need to hone the skill for whatever you feel is mentally sapping you or depressing you or impacting you to the degree you need to put it all in a location to control it better.
Hope this helps, YMMV... not a psychologist but I did stay at a Holiday Inn Express once