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#### 5.3.3 Tracking your habits

Org has the ability to track the consistency of a special category of TODOs, called “habits”. A habit has the following properties:

1. You have enabled the `habits` module by customizing the variable `org-modules`.
2. The habit is a TODO, with a TODO keyword representing an open state.
3. The property `STYLE` is set to the value `habit`.
4. The TODO has a scheduled date, usually with a `.+` style repeat interval. A `++` style may be appropriate for habits with time constraints, e.g., must be done on weekends, or a `+` style for an unusual habit that can have a backlog, e.g., weekly reports.
5. The TODO may also have minimum and maximum ranges specified by using the syntax ‘`.+2d/3d`’, which says that you want to do the task at least every three days, but at most every two days.
6. You must also have state logging for the `DONE` state enabled, in order for historical data to be represented in the consistency graph. If it's not enabled it's not an error, but the consistency graphs will be largely meaningless.

To give you an idea of what the above rules look like in action, here's an actual habit with some history:

         ** TODO Shave
            SCHEDULED: <2009-10-17 Sat .+2d/4d>
            - State "DONE"       from "TODO"       [2009-10-15 Thu]
            - State "DONE"       from "TODO"       [2009-10-12 Mon]
            - State "DONE"       from "TODO"       [2009-10-10 Sat]
            - State "DONE"       from "TODO"       [2009-10-04 Sun]
            - State "DONE"       from "TODO"       [2009-10-02 Fri]
            - State "DONE"       from "TODO"       [2009-09-29 Tue]
            - State "DONE"       from "TODO"       [2009-09-25 Fri]
            - State "DONE"       from "TODO"       [2009-09-19 Sat]
            - State "DONE"       from "TODO"       [2009-09-16 Wed]
            - State "DONE"       from "TODO"       [2009-09-12 Sat]
            :PROPERTIES:
            :STYLE:    habit
            :LAST_REPEAT: [2009-10-19 Mon 00:36]
            :END:

What this habit says is: I want to shave at most every 2 days (given by the `SCHEDULED` date and repeat interval) and at least every 4 days. If today is the 15th, then the habit first appears in the agenda on Oct 17, after the minimum of 2 days has elapsed, and will appear overdue on Oct 19, after four days have elapsed.

What's really useful about habits is that they are displayed along with a consistency graph, to show how consistent you've been at getting that task done in the past. This graph shows every day that the task was done over the past three weeks, with colors for each day. The colors used are:

`Blue`
  If the task wasn't to be done yet on that day.
`Green`
  If the task could have been done on that day.
`Yellow`
  If the task was going to be overdue the next day.
`Red`
  If the task was overdue on that day.

In addition to coloring each day, the day is also marked with an asterisk if the task was actually done that day, and an exclamation mark to show where the current day falls in the graph.

There are several configuration variables that can be used to change the way habits are displayed in the agenda.

`org-habit-graph-column`
  The buffer column at which the consistency graph should be drawn. This will overwrite any text in that column, so it's a good idea to keep your habits' titles brief and to the point.
`org-habit-preceding-days`
  The amount of history, in days before today, to appear in consistency graphs.
`org-habit-following-days`
  The number of days after today that will appear in consistency graphs.
`org-habit-show-habits-only-for-today`
  If non-nil, only show habits in today's agenda view. This is set to true by default.

Lastly, pressing `K` in the agenda buffer will cause habits to temporarily be disabled and they won't appear at all. Press `K` again to bring them back. They are also subject to tag filtering, if you have habits which should only be done in certain contexts, for example.