Just because someone stumbles, falls, crawls, falls again is no indication of failure. Failure, as has been said a million times before, is not getting back up.
And if you expect someone to stumble, they will. And then you'll confirm that you knew all along they would fall short. But the thing is, everyone stumbles eventually- if they're lucky. Most fall at one point or another, and many fall hard. You are programmed to see things as an optimist or a pessimist. Sometimes this is a result of your parents' influence, or even your job. Take the accountant that is designated to look for errors all day. They are expecting mistakes. They leave work and their brains are still stuck in this mode of scanning for mistakes. Now I am certainly generalizing, but my point is the choice is a conscious one.
As humans we have this innate desire to put people into boxes. The child spills the glass of milk because he put it too close to the edge of the table. Parent A tells the child he's clumsy. Tell him that enough times and he'll go through life with this expectation that he can't shake. Parent B tells the child "Hey let's clean this up together. You know if you move your milk closer toward the middle of the table you probably won't spill it. I used to do that all the time until I figured out that little trick." Perhaps a learning experience? A chance to bond? Silly example but it makes the point.
Another child draws something for her parents. The parents tell her that's a beautiful drawing. You know if you practice drawing you could be a great artist? In fact, you can be anything you want to be. It might be tough at times but if you stick with it, you'll succeed. It doesn't matter what it is, we believe in you.
I believe it was Einstein that once said, "Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid."
We have the power as human beings to shape others' conceptions of themselves. Most don't realize that it's a power, but some treat it as such and even consider it an obligation...to give their children all of the tools they need to succeed. But it goes beyond children. We're talking about friends, family, coworkers... The minute you tell someone they can't do something, you've planted a seed. The minute you tell someone they can do something, or achieve whatever they set their mind to, you've planted a seed. Which seed will grow? Whichever one you water.
There is an old Indian tale about the two wolves inside of us all. There is an evil, jealous wolf and a benovelent, generous wolf. An elder shared this with his grandson, to which the grandson asked 'but which wolf wins?' The old Cherokee replied, 'the one you feed.'
What I'm saying, in so many words, is treat others as if they are currently at their greatest potential. If you expect someone to fail, they will. If you expect someone to succeed AND arm them with the confidence and resources, they will. Now you are fostering an environment in which they will exceed their full potential. Water the seed of success, feed the peaceful wolf, don't put people in boxes, and allow the human beings you surround yourself with to reach their maximum potential.