I interpret this that we can learn from failures and rejections.
As they said, "learn from your mistakes", "charge to experience",  as for me thru mistakes and experiences we can improve to be better.
When there are rejections, do not considered it as failures, think of that it may not be the right time or God has a better plan.
If there are difficulties encountered enjoy it, for it is only for some time and think that nothing is permanent in this world aside from change. Think that everything will change, our life, our world is like a ball, that is round  that will roll and bounce.