Sean Conway's
496 Challenge.

The premise is simple. On the 1st of the month, get out and run 1km. Run 2 on the 2nd. Follow this pattern and in 31 days you'll have run 496km.

If the incremental challenge isn't for you, try it in reverse, do "The Pyramid" where you build up for the first half of the month and taper off towards the end, or leave it up to fate and have the app decide your schedule in "The Tombola".

Be sure to log your runs on the Dangelo app. Once you're done, send your results to Sean to claim your finishers certificate and medal!