I love doing wedding photography. It can be pretty damn stressful for me as I worry so much about something going wrong. I don't want to be the guy that screws up the weddings pictures like that. Even with so many people bringing digital cameras to weddings now a days, someone is paying you to do a job and expecting you to perform beautifully. Its a lot of pressure, but I seem to do my best work (with anything) under a lot of pressure and stress.
Its awesome being a part of someone's memorably day though. Even if you don't know the people at all you really form a connection with them. You get to know them if you are perceptive enough. Seeing that much love and affection, the best of who they are as individuals and as a couple is pretty powerful. As with most things, seeing the best means seeing the little things.
For example, at the wedding this past weekend it was pretty windy during the ceremony, which was outside on a beautiful lake. The bride's veil was flying all over the place and in one of my favorite pics the groom adjusts it for her with a gigantic smile on his face. Its one of my favorite pics from the wedding, not so much because of the quality of the photo, but because it shows who he is as a person. The maid of honor could have done that for her, but he reached around and did it himself. It tells me what a caring person he is and how the little things matter to him.
This... this is why I love shooting wedding pictures. That, and free cake.