How do I stop worrying so much?

Okay, my name is Alison, and I am 24. My fiance, Christoph, is a bail enforcement agent (a bounty hunter, more or less.) It’s a very dangerous job, as you can imagine, and it makes things difficult sometimes; he works a lot of long hours, and I worry about him whenever he leaves for work. He is only 33, and he has already been shot twice. Luckily, they were not too serious; one in the arm and one in his shoulder. He healed just fine but nothing can seem to scare him out of this career. He loves what he does, and I would never ask him to stop doing what he has a passion for. I worry a lot, though. I am home a lot more than he is, and I spend a fair amount of time alone. My family lives far away, and most of my friends are already married, so I try to find other things to occupy my time, so I don’t just sit around being sick with worry. I can’t help it sometimes, though. The thought of losing him makes my breath catch in my throat. He is such a gentleman, and I have never had anyone treat me so well. I love him more than anything and I know that there is no one in the world that I would rather be with, which is why I worry so much. How can I keep myself from thinking about it constantly? I feel like a crazy person. Whenever I’m alone, it seems like I just think up the worst possible situations. I just love him so much, and I worry about him getting hurt or killed… Advice?