Every day you get to decide if you want to spend time exercising or performing a reinforcing sedentary behavior. The trick to making the economics work for you is figuring out what makes the sedentary option appealing, and then how to apply it to an action behavior.
For example: a group of friends get together once a week for happy hour and to socialize. They found that what they enjoy most about these weekly meetings is the socialization, not the location. Instead of meeting at a restaurant, these women choose to meet at a local park for an hour of active socializing on the paths and trails. By understanding the factors that appeal to us in different activities, we can apply them to health promoting activities.