Getting nervous over voting is the same as getting nervous over flying.
You know how they tell you that you're more likely to die in a car accident than a plane crash, and yet people drive all the time without fear and still many people clench up when boarding a plane?
It's because of control. If you're driving a car--or say a friend or a family member is driving a car---you feel in control. You see the road. You see the driver. You know what's going on.
But when you're on an airplane, you're stuck in the seat, there's a pilot you don't know flying the plane, the pilot's up in the cockpit and you can't see him/her, all you get is his/her voice over the intercom like he/she is God or something, and everything is taken out of your control. And you're stuck with blind faith that the pilot knows what he or she is doing.
Now think of an election like an airplane flight, but instead of just one pilot, you have thousands, or even millions or tens of millions of pilots. And you just hope to God that a majority of those pilots know what they are doing and lands you safely at your destination.