Human beings are fallible, or put simply, able to fail! There's no doubt there, as long as we are human, failure will always be an option. Try as we will, we may, and often will, succeed more often than we fail, but be sure that at some point, we ARE going to fail; it's a fact of life!
I try to look at failure as Edison did; 'I’ve tried everything. I have not failed. I have just found 10,000 ways that won’t work'. The best we can do is try; sometimes we succeed right away, sometimes it's not till we have failed many, many times! When we persevere, however, we have succeeded, whether it's in figuring out that it can't be done, or just in finding 10,000 ways it won't work ( 'try, try again' )!
There are those out there who will try to tell you, 'if you just believe', you can do anything you want! We've yet to see any of them 'add one cubit to his stature' or sprout wings and fly! Yet, with the progression of technology, we have, almost literally, seen men 'sprout' wings and fly! Wilbur and Orville Wright, much as Edison, I'm sure, found many, many ways that it wouldn't work before they finally figure out one that would! Their experimentation led to the first man-made flight ( unless you count Greek myth ) and, 'O, how far we have come since then!'