swimming - helps, reduces BP.
some other kinds can increase instead.
By far I find listening to relaxing tranquil music (find good ones) in youtube is the best and quick in calming down.
BP is simply hyper tension in most cases. Follow your religion and spend some time in some meditation, say, after lighting a diya, reading some devotional books. Make sure the peace is carried on during rest of the day and when dealing with others. Remember human values in nature will never change. Do not exert perfection on others. It gives complete cure.
If you do not have inclination to be devotional, then at least read for 1 hour any school/college text book you had liked. I remember one of my directors used to study for 1 hour then only start his day at office. If you like physics book from your college days, get it, study and solve some problems for some time. This kind of concentration also helps.
In all these cases make sure you are alone when studying/reading and absolutely no distractions.