Author Shelly Crane gives the simplest advice on her blog: http://shellycrane.blogspot.com/2014/04/im-so-thankful-for-those-rejections.html
She celebrates the anniversary of her first rejection letter. Why? Because that was the start of many rejection letters, soon followed by her first published book. Nineteen books later and she is still going strong!
"All the happenings we think of as failures in our life are simply reminders that something better is in store for us. If something doesn't work out, it just means that what is meant to be is still being prepared; it's under construction. The rejections are simply the caution tape, keeping us from seeing the final result until it is completely finished- because only then can we truly appreciate the purpose and reason for it all." -Me