youll grow to love working out that early...give it a couple weeks.....give your body time to adjust!
When you can, try and do any OTHER workouts you do during the week around that time as well... If you just wake up at 5 one day a week to wake up-- well...i bet youll struggle every time.
Wheni am marathon training i wake up as early as 2 30 am to get my runs in before work.....
nowadays the alarm is set for a much more reasonable 3 45.....
its all in your perspective. I just goto bed really early and miss out on crappy television shows!
Good luck you