Second Nephi 4:26

O then, if I have seen so great things, if the Lord in his condescension unto the children of men hath visited men in so much mercy, why should my heart weep and my soul linger in the valley of sorrow, and my flesh waste away, and my strength slacken, because of mine afflictions?

Nephi asks searching, searing, introspective questions. In essence, he says his spirit is willing but his flesh is weak. Why do we give in and then get discouraged? Because it is our fallen mortal nature. Why do I fail every day? Because somewhere along the line every day I forget to lean on the Lord, and I try to operate on my own. The thing is, God wants us to learn self reliance and to be agents. But in this life we cannot walk many steps without his strong and steady hand. Like Peter, we may have the faith to get out of the boat, but when the storm rages and the waves are high, we get distracted. We catch ourselves sinking, and if we are wise, we call out to the Lord to save us. And every day he does save us.