we cannot directly control our heart rate
but we can control our breathing which can control our heart rate
I think excercise, at least for me, is a necessary part of dealing with this, that and meditation/mindfulness to retrain the brain. I exercise every day from 15-40 minutes. I just check my heart rate on occasion, many days not at all, but if it is below 140 i just remind myself my heart is a muscle that needs exercising just like my other muscles.