And when they had sung a hymn, they went out to the Mount of Olives. And Jesus said to them, “You will all fall away, for it is written, ‘I will strike the shepherd, and the sheep will be scattered.’ But after I am raised up, I will go before you to Galilee.” Peter said to him, “Even though they all fall away, I will not.” And Jesus said to him, “Truly, I tell you, this very night, before the rooster crows twice, you will deny me three times.” But he said emphatically, “If I must die with you, I will not deny you.” And they all said the same.
Mark 14:26-31.

It was not only Peter who boasted of being willing to die. All the disciples agreed. Although they did scatter when Jesus was captured, they all returned to Him (except Judas Iscariot,  of course) and all but John died as martyrs.

We all have feet of clay and have chickened out during a test of our faithfulness. But it is never too late, as long as you have breath, to return and be restored.