17 days out!
I was very sleepy until day 6 I started to build up my walking, 10 minute/15 minutes/20mins etc per day each day until I could do 30 minutes with ease, I felt this helped with energy levels also the most important thing is eating and drinking!
I suggest instead of eating large meals space several smaller ones, eat lots of fruit especially stuff like oranges, pineapple and stuff high in vitamin C. Also eat more than normal, you need to recover,
Sleep 8 hours straight then follow with 1 hour nap or 2 if you can during the day, main thing is drink clear water this also helps with energy levels,
Coffee, 2 cups per day! Nice for the poop and to keep you focused