I have a friend who is an author. Mark has published multiple books in the past decade. He served as a pastor for 15 years but has spent the past 10 years writing and submitting manuscripts. 
He called me the day the first manuscript was accepted. He was floating on air. Mark is the father of three daughters, and I joked that he probably was more excited about the book than he was about the birth of any of his girls. 
That, of course, was an exaggeration, but the joy he felt and expressed was great. As I sat and talked with him that day, I learned a great deal about his efforts.
You see, Mark had written and submitted many manuscripts to numerous publishers before the first one was accepted. Time after time, he had received rejection letters.
Some came with helpful advice and small bits of encouragement. Some were nothing more than a slap in the face.
But he kept writing. He continued to submit manuscripts. Finally, there was acceptance. Finally, someone saw in him what others had not seen. Finally, all of the work was validated. And now, he is an author! 
We all know the story of Abraham Lincoln. He failed miserably and was defeated numerous times when he ran for office. Many believed that he was nothing more than a failure. But he refused to quit, and now most would agree that he was one of the greatest presidents in the history of our country. 
I don’t know about you, but I don’t like to fail. I want to succeed every time in all that I do. 
I’m a big baseball fan. Chipper Jones is my favorite current player, and I have to remind myself that he fails during approximately 70 percent of his at-bats. And he probably is bound for the Hall of Fame someday. 
What do you do when you fail? You have several options.  You can quit. You can keep doing exactly what you are doing without making any changes. Or, you can adapt but keep at it. 
God knows that we sometimes will fail. That is why Jesus came. He redeems people who have failed. But he only redeems those who recognize their failures and seek his help.
I want to encourage you not to quit just because you aren’t successful, but don’t be so stubborn that you won’t make changes. Pray. Adapt. Keep at it. Whatever else you do, don’t quit.
God can use you to accomplish his purposes, but you have to keep at it. Are you willing?