Motivation is a Mac OS X screen saver inspired by Alex MacCaw's Motivation Chrome Extension. From Alex:

…screen with a counter showing your age incrementing in real time… It’s a simple tool, but it helps me think about perspective a bit more, which in turn helps me optimize my time.

You can configure your age once you picked it in Screen Saver Preferences in System Preferences.

Download the latest release. Unzip and double-click.

Xcode 7.0 beta 5 is required to build Motivation since it's written in Swift 2.