It seems that using one of these…
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…set to about 70% of your maximum inspiratory effort (100% being just unable in inhale) for 30 inspirations per day will significantly lower your blood pressure and improve one's endothelial function (the delicate inner layer of ones arterioles that produces the potent vasodilator nitric oxide, which controls ones blood pressure). It is just as, if not better than, blood pressure medication and easy to comply to. Read the paper and there are many others.