You always have to prepare for the obstacles that are going to come. Consequently, when they do come, it doesn't affect you mentally near as much as when you're unprepared for them.
The answers to these questions will determine your success or failure. 1) Can people trust me to do what's right? 2) Am I committed to doing my best? 3) Do I care about other people and show it? If the answers to these questions are yes, there is no way you can fail.
After landing his invasion forces on the shores of some country, the sixteenth-century Spanish conquistador Hernan Cortes would immediately burn his own boats. He was sending his army a message: "We can't turn back. Either we succeed here or we die here." Excuses were not an option.