1. We're not used to being active. For many people, structured exercise is something they've never had to do before. As a result, bringing exercise into an already busy schedule often feels like having an unexpected (and unwelcome) guest come for a visit. Having to rearrange your schedule to accommodate this guest causes stress, anxiety and even resentfulness. That's often how we feel when we realize that starting an exercise program may require major changes in how we live and schedule our time.