When I was sixteen I had a six pack and worked out by smoking ten a day, drinking nine pints a week and walking home with a doner kebab (with turbo chilli) at the end of a night out.
Fifteen years on, my waist measurement is exactly the same although the six pack is slightly fuzzy around the edges and occasionally becomes a four pack or even a two pack depending on the season.
I no longer smoke, nor do I eat red meat. My exercise regieme is as follows:
Monday: Gym
Tuesday: Swim 1 mile
Wednesday: 1 hour hardcore power pacing
Thursday: Swim 1 mile
Friday: Gym or 2 hours cycling
Saturday: Swim 1 mile or gym
Sunday: 2 hours cycling / swim 1 mile