The issue:
It is frequently asserted that people are addicted to cell phones. If only there were a technical solution to this problem!
Proposal:
Here’s a simple solution to discourage casual cell phone use: a cell phone with two features:
- A strict limit on the amount of time you can use each program. (This feature already exists.)
- A hand crank on the side of the phone (Figure 1) that lets you circumvent the limit while you turn the crank.
- (Turning the crank also charges the phone battery, which makes this an eco-friendly idea as well.)

Alternatives to the crank could also be employed: foot pedals, a bellows, or The Wheel of Pain from the 1982 Conan the Barbarian movie.
The crank could also be useful in other situations (Figure 2).

Conclusion:
This eco-friendly idea is guaranteed to be a staple of future phone / tablet / laptop design.
Alternative Version:
An alternative formulation of this idea would be to not meter usage by time, but just require a user to turn the crank 50 times before an app will launch or a web page will load.
PROS: Discourages casual phone use out of boredom / habit. Provides a good arm workout, especially if you remember to flip it 180º occasionally to work out both arms.
CONS: Might not actually reduce phone use, but now there would be an annoying grinding sound of people turning cell phone cranks everywhere. Would increase the frequency of dropped phones.