St. Bernard of Clairvaux wants us to know that even in the midst of the struggle - whether it be with mortal sin or venial sin, worldliness or temptation, perseverance in prayer or growth in virtue, loving or forgiving - we profoundly need to "lean on the Beloved". Bernard knows that to "fight against yourself without respite in a continual and hard struggle, and renounce your inveterate habits and inborn inclinations" is very hard, impossible really, without the help of the Lord.
But this is a hard thing. If you attempt it in your own strength, it will be as though you were trying to stop the raging of a torrent, or to make the Jordan run backwards (Ps. 113:3). What can you do then? You must seek the Word... you have need of strength, and not simply strength, but strength drawn from above (Lk. 24:49).
The words from Hebrews come to mind:
Therefore, since we are surrounded by so great a cloud of witnesses, let us also lay aside every weight, and sin which clings so closely, and let us run with perseverance the race that is set before us, looking to Jesus the pioneer and perfecter of our faith, who for the joy that was set before him endured the cross, despising the shame, and is seated at the right hand of the throne of God. (12:1-2)
The journey up the summit of the mountain of God (or Mount Carmel, as St. John of the Cross calls it) is difficult. And St. John of the Cross, St. Bernard of Clairvaux, St. Catherine of Siena, St. Thérèse of Lisieux, St. Teresa of Avila, St. Augustine, and St. Francis de Sales know that it's impossible to attain the summit - spiritual marriage in this life, beatific vision in the next, without leaning heavily of the Beloved.
As Bernard, in accord with his fellow Doctors, explains:
"Who shall ascend the mountain of the Lord?" (Ps. 23:3) If anyone aspires to climb to the summit of that mountain (Ex. 24:17), that is to the perfection of virtue, he will know how hard the climb is, and how the attempt is doomed to failure without the help of of the Word. Happy the soul which causes the angels to look at her with joy and wonder and hears them saying, "Who is this coming up from the wilderness, rich in grace and beauty, leaning upon her beloved?" (Song 8:5). Otherwise, unless it leans on Him, its struggle is in vain. But it will gain force by struggling with itself and, becoming stronger, will impel all things towards reason... bringing every carnal affect into captivity (2 Cor. 10:5), and every sense under the control of reason in accordance with virtue. Surely all things are possible to someone who leans upon Him who can do all things? What confidence there is in the cry, "I can do all things in Him who strengthens me!" (Phil. 4:13)... "Thus if the mind does not rely upon itself, but is strengthened by the Word, it can gain such command over itself that no unrighteousness will have power over it" (Ps. 118:133). - St. Bernard of Clairvaux
The Good News is that the Beloved loves to be leaned on!