"You look down today, what's going on?" my wife says when I get home from work. I answer, "I don't know, I was just worrying about this project at work." What's wrong with this picture?
The mental error is that I was treating worry like an activity instead of treating it like a signal. It's all about the self talk. When there is some outstanding issue that needs attention, it is easy to jump straight to thinking about the issue, even though you can't really do anything about it at the moment. The reality is that if I'm going to resolve the outstanding issue, I need my computer open, I need to talk with a team member to figure things out. I need to write some code or run a query to see where things stand.
But if I attempt to sort things out mentally while I don't have everything I need to make progress on an issue, it's easy to spin my wheels and fall helplessly into a non-productive mental loop.
On the other hand, if the "outstanding issue" thought comes into my mind, and I call it worry (which it is), and instead of holding onto that thought, if I treat it like a signal, like an alarm bell, like a red light, then that frees me up to act on the signal. Instead of treating the "outstanding issue" thought as an activity waiting to be engaged in, if I treat it as an self-alert, then I can move to deal with it at a later, more appropriate time.
The question becomes: "What action can I take right now to make sure that the outstanding issue is dealt with at the appropriate time and place?" Maybe make a reminder on an index card and put it in my work pants pocket. Maybe make a reminder on my phone. Maybe send myself a memory jogger in email. Maybe write a card and stick it in the Trello / Getting Things Done inbox. It just needs to be something that I am confident will get my attention and lead me down the right mental path at the time when I know I will have resources to deal with the issue.
Any time spent on worry as an activity (beyond dealing with the reminder for the future time/place) I now believe to be worse than a total waste. Not just worthless time spent, but also a drag on the rest of my life. Any unnecessary, anxiety-provoking activity drags me down, makes me less capable of living my life in a worthwhile, enjoyable way.
Why did I not see this earlier in my life? What could I have done to have learned this earlier in my adolescent / adult experience?