Train and do it, you will not regret it

Other than the obvious things you'll need like good fresh cloths and good maintained bike, I would highly recommend a good support team even if they are on the other end of a phone. You will hit limits - just don't give up, remember the reason for doing this and what to look forward to the next day.

Plan your route to places you want to cycle pass, it will make it more interesting and set little goals.

Focus on one day at a time and enjoy the surrounds, the people and animals you will meet.

The exciting part is starting, meeting people and the ending is a great feeling, specially when meet by people suffering from this crappy thing.

I wish you the very best