I think that life is difficult. People have challenges. Family members get sick, people get older, you don't always get the job or the promotion that you want. You have conflicts in your life. And really, life is about your resilience and your ability to go through your life and all of the ups and downs with a positive attitude.
I always want to say to people who want to be rich and famous: 'try being rich first'. See if that doesn't cover most of it. There's not much downside to being rich, other than paying taxes and having your relatives ask you for money. But when you become famous, you end up with a 24-hour job.
It was my duty to shoot the enemy, and I don't regret it. My regrets are for the people I couldn't save: Marines, soldiers, buddies. I'm not naive, and I don't romanticize war. The worst moments of my life have come as a SEAL. But I can stand before God with a clear conscience about doing my job.
No matter how good you think you are as a leader, my goodness, the people around you will have all kinds of ideas for how you can get better. So for me, the most fundamental thing about leadership is to have the humility to continue to get feedback and to try to get better - because your job is to try to help everybody else get better.