The most valuable skill that you can learn is to be self aware in terms of where you are. Quit worrying about all the things that you did, just try to get better to day. Being able to gauge yourself a from a realistic fashion is a really good way to stay humble. The first mental training to at's attaining belief in yourself.
Humility is huge. Not just for living a good life. For running a successful business, too. According to Andy Frisella, humble leaders inspire employees and customers, and humble businesses improve and dominate.