HI
as age goes up any person can develop high blood pressure
more common in person who have family history or stressful life style ,tobacco use in any form etc

Risk wise, long term it has many risk in form of development of heart problem , brain stroke , kidney damage , vision related issue , but all this are long term uncontrol Blood pressure related issue thats why , necessary to control BP and medicine to be continue for long term and to be taken regularly
in your case its detected first time and its borderline elevated so you can start life style modification
like adopt DASH diet ( low in salt intake
quit use of tobacco and alcohol if you are using it
regular walking
do meditation , yogas
do regular check up of your BP , if its remains high after stating life style modification then you need to start medicine
take care

Hi Ramesh
Welcome to HCM
High Blood pressure or Hypertension is detected mostly by medical check ups as most of the patients are asymptomatic,as far as your BP reading is Diastolic is 100 which is high and Systolic 120 mm of Hg is normal if it is your first high reading kindly repeat BP measurement 2-3 times in a relaxed state to decide about you have Hypertension.
These are called Pre hypertensives and can take Certain life style modifications to keep BP in normal range.
Reduce Common salt cosumption to
If you are over weight reduce to ideal level by diet and exercises.
If you use tobacco in any form must be stopped
If alcohol is there then stop it or at least moderate the use to minimum.
Try to reduce stress by meditation and yoga and Pranayam etc.
Take fresh fruits in diet.
If all these measures fail and BP readings are high one has to take antihypertensive drugs.
Let us hpoe for best
Take care
Best of Luck