meditation and biofeedback
Step-by-step explanation:
you need to learn to calm yourself. you can find meditations all over the internet it's not just sitting and humming. look for guided meditations to help you relax and let go of negative thoughts.
if it's not going to matter in 100 years, let it go. if you can't control it let it go.
with biofeedback, it's kind of like meditation. but you focus on bringing your blood pressure down.
i use a pulse oximeter and if my pulse is too high, i take deep breaths and focus on bringing pulse down.
good luck