Trigger the physical activity. A trigger is defined as an
alert that should be presented to users at a moment when
they can perform the behavior [3]. It can be designed: i) to
inspire the desirable behavior by including motivational
elements (i.e. images representing the positive effects of
performing the behavior), ii) to make users aware that the
behavior is easy to do (for persons who lack abilities for
executing the behavior), and/or iii) to provide reminders
(since if a user is highly motivated, he may just need to be
reminded to take action) [3]. As we are designing for
elders who are able to exercise, we decided to provide the
following timed-notifications as triggers to encourage
elders to achieve their exercising goals: i) reminders for
exercising, and ii) notifications to encourage them to finish
the physical activity; that is, while they are exercising,
they will be aware of how close they are to reach the
proposed exercising goal.