Day 5 and I'm Tired

It's day 5 of my P90X 90 days journey and I am tiirreedd. Did Legs and Back, Cardio X and AB Ripper X. Gawd. I'm tired.... :s Insane workout! (Decide.Commit.Succeed.)

1800 Calorie Diet In 3 Weeks

I have to stay within the 1,800 calorie range of the program. When I read P90X's nutrition guide, it says there that the 1st three weeks should be fat shredding phase and in order to do that I have to minimize my calorie intake. Hard. but I can do it. It's my 3rd day in the program and I did Shoulder - Back and AB Ripper X afterwards.