Here’s something I do which needlessly raises my stress: I too often ponder the worst case scenario after a situation is out of my control.
For example, I email someone important, and until I’ve heard back from him, I think about the worst case (“He hated it, forwarded it to his three VIP buds and ridiculed me”) or (“He’s not going to respond because he thought the idea was terrible”). This is not helpful since I’ve already sent the email.
While sometimes thinking through the worst case scenario can be helpful in getting us to do things we’d otherwise avoid — what’s the worst thing that can happen by doing karaoke in a club? I get a little embarrassed? I’ll do it! — it’s only helpful before action is taken.
I guess this is part of the larger idea of living in the present. We ought not obsess about the past nor worry excessively about the future. (There’s a difference between prudent planning for the future and counterproductive worrying; just like there’s a difference between learning from the past and “obsessing” about it.) In my email example above, if the worst-case scenario were to happen, best to deal with it then, in that moment.