The Underground Strength Training crew is about to be subjected to a 24 hr. workout, but as entrepreneurs they are well accustomed to that dynamic. They have some great insight (Like the failsafe man in the mirror test) on what it takes to navigate through the hard times in service of a passion. http://www.spartanuppodcast.com/038 
Lessons:1. Look at sacrifices made for success as an investment.2. If you can delay gratification, you will be more successful in all areas of life.3. Find your why by telling it to yourself in the mirror since it’s almost impossible to lie to yourself this way.4. Surround yourself with supportive people of a like mind, if they can’t be found in person find them in books and podcasts.