To make sure that cowardice does not make you betray the confidence God has placed in you, you must avoid the presumption of naively underestimating the difficulties that you will meet in your Christian life.
These difficulties shouldn't surprise us. As a consequence of our fallen nature, we carry within us a principle of opposition, of resistance to grace. It comes from the wounds inflicted by original sin, and is aggravated by our own personal sins. Therefore we have to strive ever upwards, by means of our everyday tasks, which are both divine and human and always lead to the love of God. In this we must be humble and contrite of heart and we must trust in God's help, while at the same time devoting our best efforts to those tasks as if everything depended on us.
As we fight this battle, which will last until the day we die, we cannot exclude the possibility that enemies both within and without may attack with violent force. And, as if this burden were not enough, you may at times be assailed by the memory of your own past errors, which may have been very many. I tell you now, in God's name: don't despair. Should this happen (it need not happen; nor will it usually happen) then turn it into another motive for uniting yourself more closely to Our Lord, for he has chosen you as his child and he will not abandon you. He has allowed that trial to befall you so that you may love him the more and may discover even more clearly his constant protection and Love.
Take heart, I insist, because Christ, who pardoned us on the Cross, is still offering us his pardon through the Sacrament of Penance. We always 'have an advocate to plead our cause before the Father: the Just One, Jesus Christ. He, in his own person, is the atonement made for our sins, and not only for ours, but for the sins of the whole world' , so that we may win the Victory. (Friends of God, 214)
 1 John 2:1‑2