I get a kick out of all my co-workers with the "Oh, I gotta start eating healthier/exercising...." line but 98% of them never do anything about it except talk the talk.
I'm fortunate enough to only live 2.5 km from work, so I walk back and forth everyday. This only burns about 250 calories but the biggest thing is my diet. I work on a 2000 calorie diet (exercise incl) and it maintains my weight around 132ish. I'm 5'6" and not a 'big' guy to begin with but after leaving the military, 2 years later I was up to 148 lbs and had a 'gut'.
I use to go to the gym at lunch but my 42 yr old body started to reject this to no fault of my own. I couldn't learn to take it easy and pushed myself too far. I would really like to be more active but have accepted I am getting older and being able to just maintain my current weight with little exercise and diet will have to suffice.
Weekends are 'my' time and I eat/drink what I want; its the only way to keep up with this life style without going crazy