The common denominators are
1) several attempts at the distance
2) a long term racing plan
3) a consistent training plan
2:22 is the equivalent to a 3:53 1500. It can be accomplished by many athletes.
Probaly the most important ingredent is listening to your body and adjusting your training. You have plenty of time.
You should experiment with training. Some people thrive on 100 miles/week. Others crumble. Both are capable of running under 2:22. Your task is to figure out the best way to get there.
Good luck to all of you with this same goal! I hope there are >300 people at the starting line in '08.