Vocal prayer is…

Vocal prayer, without the heart attending it, is superstitious and wholly unprofitable. To pray without recollection in God and without love, is to pray as the heathen did, who thought to be heard for the multitude of their words.
–François Fénèlon (1651-1715)

What we call prayer…

When the time comes to present ourselves before His divine Goodness to speak to Him face to face, which is what we call prayer, simply the presence of our spirit before His and His before ours forms prayer whether or not we have fine thoughts or feelings…He is touched with the prayer of a soul so simple, humble and surrendered to His will.
–Saint Jane Frances de Chantal (1572-1641)

Your own prayers…

Accustom yourself to pray your own prayers. For instance: it is the essence of evening prayer to thank God for the day and everything that happened, both pleasant and unpleasant; to ask forgiveness for all wrongs committed, promising to improve during the next day; and to pray that God preserve you during sleep. Express all this to God from your mind and from your whole heart.
–Saint Theophan the Recluse (1815-1894)

Prayer is conversation…

Prayer is just conversation with God: listening to him; speaking with him; gazing upon him in silence. The best prayer is the one in which there is the most love. Adoration, wordless admiration, that is the most eloquent form of prayer: that wordless admiration which contains the most passionate declaration of love.
–Blessed Charles De Foucauld (1858-1916)