Intensity: (how hard?) - Intensity can vary from very light to very hard and can be monitored on the basis of training heart rate or your own subjective impression of how hard you are working.
Frequency: (how many?) - Start with three days a week and work towards seven days a week.
Duration: (how long?) - Begin with a minimum of 20 minutes throughout a day with a goal of increasing to 60 minutes a day. This can be done in multiple 10-minute sessions or in one longer session.
Mode: (what kind?) - Structured (walking, running, cycling, swimming, resistance training) or unstructured (gardening, household cleaning, walking to work)
