One can live well without requiring hours each week engaged in monotonous exercise. Significant strength increases occur exercising as little as once or twice a week IF it's the right exercise program with the right trainer.
Such a workout can be very demanding, but people or any age or fitness level can do this and benefit from it. Clients slowly build up to a level they can handle. It is an attractive alternative for those who often don't have time for exercise.
From this Wall Street Journal article GE's Bob Wright Stays Strong By Lifting Weights Very Slowly:
“Workouts typically consist of one set of six to 12 exercises with little rest between sets…. trainers find a weight load that renders muscle fatigue in 60 to 90 seconds, and take clients through a full-body workout in approximately 30 minutes”.