A baseball player who expects to excel in the game without adequate exercise of his body is no more ridiculous than the Christian who hopes to be able to act in the manner of Christ when put to the test without the appropriate exercise in godly living. - Dallas Willard, Spirit of the Disciplines, pg 4-5.

Christ didn't go into the desert hoping he could muster up faith on the spot to beat the temptations he would face. He went into the desert after decades of preparation and when he was tempted he relied on the Word of God to sustain him in the moments of crisis. He didn't will himself through it, he relied upon what had sustained him his whole life up until that point.

Our mistake is to think that following Jesus consits in loving our enemies, going the 'second mile', turning the other cheek, suffering patiently and hopefully - while living the rest of our lives just as everyone around us. - Spirit of the Disciplines, pg 4.

Jesus calls us to be set apart from the rest of the world in how we live, everyday, not just on Sundays. If we are Christians then we are Christians at work, at home, in public, in private, on vacation, in the hard times, and in the good times.

We cannot expect to be able to live a godly life in the moment (in public, or most especially in private) if we are not preparing ourselves to do so on a daily basis. It's not possible. We must devote ourselves daily to God and his way of life, so it says in Psalm 1:

Blessed is the man who walks not in the counsel of the wicked, nor stands in the way of sinners, nor sits in the seat of scoffers; but his delight is in the law of the LORD, and on his law he meditates day and night. He is like a tree planted by streams of water that yields its fruit in its season, and its leaf does not wither. In all that he does, he prospers. The wicked are not so, but are like chaff that the wind drives away. Therefore the wicked will not stand in the judgment, nor sinners in the congregation of the righteous; for the LORD knows the way of the righteous, but the way of the wicked will perish.

So how do we even begin to do this?

The secret involves living as he(Jesus) lived in the entirety of his life - adopting his overall life-style. Following 'in his steps' cannot be equated with behaving as he did when he was 'on the spot'. To live as Christ lived is to live as he did all his life. - Spirit of the Disciplines, pg 5.