I was a shy and quiet kid, so much so that I used to get in trouble at school for not answering questions when called on, even though I knew the answer. Moving around a lot forced me to get over that and the more excited, passionate or angry I get, the more my volume goes up. My friends have to remind me to quiet down, especially if I am expressing my point of view on something controversial. Once I was getting heated in a topic with a coworker that I was riding to a conference with and she started stating " I agree, I agree!" because she thought I was yelling AT her instead of just yelling in general.