I interviewed 21 self-made billionaires about their secrets to wealth and success-here's what I learned

It doesn't matter when you do your routine activities. What counts is that you commit to doing them - even when you don't feel like it.

The billionaires I interviewed are some of the most disciplined people I've ever met. They set extraordinarily high standards for themselves and the people around them.

In sports, for example, you can't achieve great results if you don't have enough discipline to train regularly. The same applies to your life and career. Limit the distractions and temptations that hinder your progress. Show up. Be eager to grow your skills.