The cell phones can count your steps. Some can even take blood pressure and pulse. It can take temperature with an external probe.
Smart watches can take blood pressure/ pulse, count steps, monitor sleep patterns.
All of these allow patients to report real data to their doctors & nurses.
Many apps help a person by providing accountability by sending reminders and encouraging daily check-ins.
Many apps are available to remind people to take medicine on time which keeps them healthier since the medicine stays at a consistent level in the blood.