If it ain't broke, don't fix it.

That's what former Marine, Erik Therwanger, told me about the approach to leadership that he learned in the Marines.

It's also the foundation of his 90 day run.

The concept is incredibly simple – the US military has a long history of teaching young men and women how to become the best version of themselves in just 90 days.

So why not apply that same methodology to the civilian world as well?