A man walking through an elephant camp, noticed that the elephants were secured only by a small rope tied around one ankle, and nothing else. He was perplexed as to why the elephants didn't break free from the rope, as they were clearly strong enough to do so.
When he questioned a trainer why the elephants didn't try to break free, the trainer said that they use the same size rope from young elephants to adult elephants. Because they are too small as babies to break free from the rope, they are conditioned to believe that the rope is stronger than they are. They don't fight as adults because they believe the rope can still hold them.
In this case, the elephants have learned helplessness. This occurs when a person has been conditioned to anticipate discomfort in some way without having a way to avoid or stop it. After enough conditioning, the person will stop attempting to avoid the pain, even if they see a way out.
If you go through life believing that you can't do something because you've failed before, you're living with a fixed mindset. You must let go of your limiting beliefs in order to make the breakthroughs necessary for long-term success.