It used to be your age over a TON! Nice the Ton bit as that coincided with the speed you loose your licence on a motorway
Then it all changed as the drug companies wanted more and more people on blood pressure lowering drugs for life and employed scientists to build their case.
Really its still not understood! Is not a constant thing and GPs love to have something to measure
Exercise dilates tight, stressed, blood vessels and hence after the exercise the pressure goes lower.
A natural pill which does work (If you can afford it is Alistrol) Taken for six weeks before your medical and you will be amazed at the readings you get.
The highest blood pressure readings I ever got was when I was 28, through the roof!!! 30 years later still get first class meds drug free!
Wish the drug companies would put more of their $Billions into finding cures and understanding conditions rather than turning out yet more damaging drugs for us to take and for them to sell!