Besides the 10 minute morning breathing meditation exercise I constantly strive to be in the moment by manually breathing during the day. This especially helpful in stressful situations.

EDIT

Also consider the progressive muscle relaxation meditation technique. It greatly helps with anxiety and I still benefit from it today even though I did only for a few months about 4 years ago. I can recognize when I am tensing up due to anxiety and immediately relax myself.

Not the OP, but I've started a morning routine of meditating for ~10 mins, brushing my teeth, journaling, a short yoga and doing misc morning chores (make coffee feed dog etc).

I would say the "routine" aspect of these has been so much more impactful than any of the actual individual things that I'm doing. I'm sure 10 mins of yoga/meditation is better than doing 0 but it's nothing life changing. One of the issues with ADHD-like symptoms for me was inconsistency. Having a morning routine sets up consistency and a system within which I know exactly what I need to do to "succeed" for the day.

Reading the book Atomic Habits by James Clear helped me actually turn these things into habits.

10 minutes breath meditation each day (usually halfway through the work day). It doesn't matter how you do it so much as just being consistent for a long time.