You need to realize how much your mood going into smoking affects the trip. There's no real easy way to get over paranoia than to smoke somewhere that you know is safe and feel comfortable in. If you're 18 and have a heart attack, you will at least be known as the youngest person to die from a heart attack. Heart failure is a different story but unless you've been deathly ill for a long time I wouldn't worry. My perscription would be to get more exercise.