There is a medical thread on PPRuNe so i suggest you search through that... It is specifically aimed towards class 1/2 medicals..
In relation to your question, I dont think you have to take it to that extreme.. I didnt and I passed no probs at all, saying that I train three times a week playing gaelic football.... but i really dont think you would have to change you lifestyle and eating habits for it........
HOWEVER,, avoid constantly eating lots of junk food, as this may come back to hunt you in later years such as Diabetes and thing of that nature!!!! Try and make sure your not dieing of the flu and cold before it, (not something people can help) but if you are out running, make sure you waer something warm!!!!
thats pretty much it... it not as bad as you think!!!!
p.s Make sure you get plenty of sleep and rest a week before it as tiredness and stress tends to show itself in the eyesight front.....
good luck with it!!!!