Tenacity identifies the fear that stops you, and allowing the higher part of your brain function to work with the fear so that you move forward anyway. As most humans endeavoring to go after something they value or desire, tenacity is exercised daily (or moment by moment). 

Tenacity and vulnerability are perhaps two of the most important muscles to strengthen. When things get hard or fears fill you with clouds of self-doubt and inadequacy, tenacity is built when you keep re-investing in: your team, your company, your work, your partnership, your marriage, or your life even when part of you would rather disengage.