I have high blood pressure, and for a long time I was afraid to even get on a coaster. When I finally took a chance, I can honestly say that I felt better having ridden it. Now I refer to them as therapy. Maybe it's just adrenalin, but who cares, my blood pressure is lower, my heart rate is lower, and I have a sense of euphoria that can last for several days.
One day at SFOT I was feelling rotten but didn't want to act like the "old" man... half way up Titan's lift hill, I began to think "this is a really bad idea". By the mcb, everything was great, and I was ready to take on anything.
Inverts are the exception. As much as I love them, my body feels the strain of the g's when my blood gets flung out to my feet.