How do you challenge yourself?

[Syringer]

Inspired by this.. http://i.imgur.com/bm4Gr.png

Anyone here mentally/physically challenge themselves? Have a goal you're working towards?

 

[Crono]

I'm working toward being fit enough to join the army (have to lose 10 lbs and be able to run 3 miles before I would even feel comfortable contacting recruiter - set a deadline of 1 month for myself), mentally I'm trying to learn biblical Greek and Hebrew, reviewing/learning physics, studying the book of Isaiah, learning history of Ancient Persia, writing a sci-fi fantasy novel, and studying to get A+ certification.