What can you learn about yourself in 21 days? More than you think, as a fun and attainable challenge a group of us participated in on a new app called "SPAR."

SPAR is an accountability app that allows you to create group challenges. The challenge is whatever you want it to be, and people must check in every day or week, depending how you structure it. If you miss a check-in, you pay a financial penalty, which goes into a pot. At the end of the challenge, the pot is split among people who checked in every day.

Go to Cernovich.com/SPAR for details on the next one.