We all have a constant roll of thoughts playing through our head and most of those thoughts are put their by our subconscious(which is trying to identify future danger and risk and so loves to focus on problems, not positive memories) or your environment and the people in it.
The first time you think about something is useful. The second and third time you think about it the thoughts might be useful. The 17th time you think about it, it probably isn’t useful unless it is a very complex problem. Thinking about that snide comment your [insert relationship] made for the 17th time probably has low utility, unless you are planning murder…
Anyone can insert something in to your stream of your thoughts. Think of a pink elephant and what that might look like. It can be a cartoon elephant if that helps. Its a BRIGHT pink. You did it, didn’t you? Everyone you interact with in your day is doing this to your constantly. They are hijacking your brain, and with every thought comes an emotional response. You are not at the helm of your thought stream. Everyone around you is, facebook is, the tv is, your boss is.
Meditation makes you sit down and shine the light on that constant movie roll of ideas playing in your head. Noticing the ebb and flow of your emotional and physiological state in response to those thoughts. When you first see them, its like realising you had a creepy person leaning over your shoulder your entire life whispering bullshit in your ear and you just hadn’t noticed. Its a fucking frightening revelation.
You then learn to switch your focus away from the thoughts that you are now seeing, to anything you like. Typically it could be your breath, but it could be the idea of your lover smiling with their arms in the air in a triumphant gesture. That might last two seconds, then your subconscious will drag you back to ruminating on a problem, and you won’t even notice it happened. Its the noticing that you are developing in a meditation practice. The noticing skill is like a muscle. The more you do it, the stronger and more reflexive it gets. Eventually, you can catch your mind picking up the useless, maddening B roll of the argument you had with your spouse about the bins not being put out, and tell your brain to jam it.