Gentle exertion may be helpful to retrain the brain to control blood flow. Try to remember the exertion levels and if it causes any head aches, next time reduce the level of exertion. That is why I said walks.

I can take very vigorous walks without letting it get my blood pressure, pulse and breathing up. I can climb the 500 foot hill behind my cabin by being deliberate and methodical. Each step is a controlled step. No excessive effort. Just a continual sustained steady pace.

As you start taking walks and such, even on your exercise bike, do not do it in a cardio format. Think of length of duration not level of effort. You should watch your breathing. If it increases, you are pushing too hard. Try talking as you walk or ride. Talking has a tendency to force you to control or be aware of your breathing. Recovery is a marathon, not a sprint.