I've probably posted this before, but it bears repeating:

In my wallet, along with the usual IDs, credit cards and cash, and along with the more survival oriented Fresnel lens, medical info card, micro pen refill and micro ferro rod, are four 81 mg chewable aspirin wrapped in aluminum foil.

In plain language for non-medical folks: Aspirin works against blood clots in the blood vessels that supply your heart muscle. The longer that heart muscle is denied blood flow by a clot blocking the blood vessel feeding it, the more heart muscle dies, weakening and eventually stopping the beating of your heart. Aspirin helps get more blood flowing sooner, or reduces the growth of the blockage. This helps reduce the amount of heart muscle damage you suffer, improving your chances of survival, and limiting the damage being done to your heart, meaning the quality of life you will be able to enjoy afterwords.

If you have no known allergy to aspirin, and you experience symptoms including some or all of the following: chest pain behind your breastbone, and/or in your jaw, neck or left arm; shortness of breath; weakness, dizziness or feeling faint, nausea or vomiting, cold sweats, anxiety or a sense of impending doom, your physician is likely to advise you to call 911 and take 325 mg of aspirin. You should also understand that heart attacks may occur with some, one, or none of the above symptoms, or other and different symptoms entirely. It is not uncommon to mistake a heart attack for indigestion, simple fatigue, a "pulled muscle" or other non-emergent problem.

IF YOU HAVE ANY DOUBT, OR ANY SUSPICION, THAT YOU MAY BE HAVING A HEART ATTACK, CALL 911 IMMEDIATELY. TIME=HEART MUSCLE. IF YOU ACT QUICKLY, YOU MAY SAVE YOUR LIFE!

Disclaimer: I am not a physician. Consult your physician, in advance, about carrying and taking aspirin in the event you experience warning symptoms of a heart attack.