One way would be to pay attention to all you thoughts, regardless of worth, writing them down, see whats recurring, and then editing them. Like ay for example, you could say to your thought, I acknowledge you, thank you for your attention, but you can go away now, you've served your purpose, and I'm grateful for the experince. Thouthts are there to remind us of things. Don't try to control them, or you'll just strangle yourself in a neverending struggle. Calm down, they are there for a reason. Relax.
Take a deep breath, and let it go...
Easy for me to say.
I tie myself in knots every day.
