Take a deep slow breath in. Slowly let it out.
Repeat 3 times.
Then just breathe normally, not so deep.
Focus on the inhale and exhale.
When you notice your mind wondering, focus back on the breathe.
It becomes easier overtime not to get distracted by your mind. There are aps on you tube you can download to help you with this.
Next Steps
consult Psychiatrist/ Psychologist
Health Tips
Do Yoga and meditation, Go for counselling session