I'd like to be a sperm donor in order to help people found or expand their family as I'm not interested to do so myself in the near future. So putting my fertility to good use by sharing it instead of ignoring it for a decade makes perfect sense to me.
Reserved, well-behaved and smart when I was a child, I see myself as a more outgoing but still calm and poised person. And you'll never see me angry. I'd add that I'm a very rational person.