I first "encountered" high BP when 37 weeks pregnant with first DD (she is nearly 45) and was ordered complete bedrest. It righted itself after the birth. Many of my ancestors (including dad and uncles) died from heart attacks in their 60s, but checks and treatments weren't as common as they now are.
My BP became an issue again 13 years ago, age 60, when I had a TIA (minor stroke) and I've been on medication ever since (Ramipril). I've had spells of "heavy" drinking (wine), smoking, and being overweight but since addressing all these, and getting regular exercise - albeit not strenuous - my BP has been pretty stable (slightly below normal) until diagnosed with A-Fib 10 months ago. That is now treated with medication and all seems well.
So yes, adjustments to lifestyle certainly help, but it ain't easy. Most of these things creep up gradually so working on them gradually too is most sustainable, and not a mega shock to bear.
I substituted Zero alcohol wine (it took a while to find an acceptable one and then a while to stop mixing it with proper wine, but now I can't abide normal stuff at all), an e-cig (now cutting down on that too) and bought a treadmill. The latter is a nuisance at the back of the lounge but living on a steep hill means I can get on it in wet/snowy/hot weather and do my bit. Might not suit everybody.
My BP is now mostly normal and have been able to reduce the medication, though I guess my ancestry means I will never be able to stop it altogether.
I've had home BP monitors for most of that time and the GP reckons even the cheap ones are fine. It is not an exact science and some days the readings are a tad high or low, but as others have said if you take readings 3 times a day they should show if there is any danger. However - do not become neurotic about it. Once it is under control, once or twice a week is generally fine.
Good luck.