I work out five days a week, and take the weekends off. Two days a week I do a half hour of cardio and a half hour of weights and core. This consists of a three minute walking warm-up, followed by five minutes of jogging, then ten minutes on a stair-climbing machine, then ten minutes on a cross-country machine. I follow that with core exercises (crunches, using the Roman chair), and various arm exercises with weights.
The other three days I spend an hour doing cardio. One day I'll do an hour on the elliptical, one day I will run for an hour (five miles--I'm not very fast), and one day I will walk on the treadmill, alternating between an incline of 9% and 21%. Sometimes I will replace one of the cardio days with a shorter, half hour workout of sprinting intervals.
I'm really jealous of the people who can maintain their weight by just walking around town. I hurt my knee and shoulder this summer and took three months off at the gym, but still walked a bunch and maintained my diet, and I put on about ten pounds, which I am now struggling to lose.