When you receive your mission call, the fourth page in your mission packet is a "General Instructions Checklist". After that page, there are several other checklists to help you prepare. There a checklist for clothes, travel, immunizations (not fun), and for mailing instructions. Even though it looks a little overwhelming, it is a step by step process.
Today I finished writing my acceptance letter. It was a special experience for me to sit down and focus on what I was committing to. I was signing a physical document that said I was going to serve for a year and a half. This may come as a surprise, but writing my acceptance letter was the first time that I didn't have doubts.
When I am acting on my decision to serve, the adversary isn't able to annoy me. When I am studying, reading, and going about my daily activities with the intentions of preparing for a mission, Satan has less affect on my attitude. so HAH. "Who's on the Lord's side, who?"
I know this seems like something I am dwelling on, but really, the adversary makes me question and doubt things that I never have before. He's just frustrated that there is such a mighty force of saints ready to spread the gospel of Jesus Christ. This is a real battle we are waging, and as my friend, Bryce, commented to me "Onward Christian Soldiers" (also hymn #246).
Though there is a lot to do and a lot to prepare, remember: We are making battle preparations.