I take my own blood pressure, record a series of a couple weeks to take to my doctor as the arm cuff of the sphygmomanometer hurts my arm such that it sends my blood pressure into orbit so is unusable.

Last year I did a month-long study of how my blood pressure reacted to various stimuli, including meditating for 5 minutes and then taking it. I did not try to get it "right" I just closed my eyes and tried to sense my posture, breathe deeply (follow my breaths) and be "quiet". I made it for a time period I knew would not drive me crazy and decided every little bit helps and, like any new skill you have to start small and work your way up; one doesn't decide to go out tomorrow and run a marathon, no, one practices first.

Anyway, just sitting as quietly as I could for 5 minutes helped my blood pressure but what seemed to help it more was if I "held" myself. Being aware of my hand on my knee, lightly fondling my knee as I took my blood pressure (the computerized monitor I have takes it 3 times, a minute apart and averages the numbers to get a more "accurate" reading) and thinking positive thoughts about my body self, how appreciative I was of my legs for carrying my overweight self, how appreciative I was of my body for taking on the weight so I could more easily deal with emotional problems, how I was working hard for us (body, mind, spirit, emotions, my whole Self) and was proud we were a team, etc.

With a minute between tests and the test taking 20-30 seconds for each of the three, it comes to about the same 5 minutes, just taking my blood pressure. Maybe you could "do" something with your mind instead of just trying to empty it, think positive thoughts or be aware of your body, your posture, your physical self and do that for 5-10 minutes and when you have that so you can do it "naturally" when you want, then try the meditation again?

Too, I took some yoga and had a great teacher who did guided imagery before and after (cool down), 15 minutes before and 15 minutes after the yoga exercises we did for an hour (so an hour and a half class, total) and I found that very helpful; maybe get a guided imagery tape, lay on the floor completely relaxed with eyes closed, etc.?