Evagrios of Pontus wrote these instructions for Christian meditation. I think it’s important to utilize the imagination and the feelings in meditation just as much as thoughts and concepts. As humans we are deeply susceptible to hypnotism and rhetoric. This is important because we often can find ourselves convinced of truths upon which we do not act because they do not affect our feelings enough to goad our will into action. And other times we might act without reference to the truth because we’ve been emotionally persuaded into a habit or action. When we meditation upon truths received in the way Evagrios instructs us, those truths can make it further into our lives.
Here it is:
“In addition to all that I have said so far, you should consider now other lessons which the way of stillness teaches, and do what I tell you. Sit in your cell, and concentrate your intellect; remember the day of death, visualize the dying of your body, reflect on this calamity, experience the pain, reject the vanity of this world, its compromises and crazes, so that you may continue in the way of stillness and not weaken. Call to mind, also, what is even now going on in hell. Think of the suffering, the bitter silence, the terrible moaning, the great fear and agony, the dread of what is to come, the unceasing pain, the endless weeping. Remember, too, the day of your resurrection and how you will stand before God. Imagine that fearful and awesome judgment-seat. Picture all that awaits those who sin: their shame before God the Father and His Anointed, before angels, archangels, principalities and all mankind; think of all the forms of punishment: the eternal fire, the worm that does not die, the abyss of darkness, the gnashing of teeth, the terrors and the torments. Then picture all the blessings that await the righteous: intimate communion with God the Father and His Anointed, with angels, archangels, principalities and all the saints, the kingdom and its gifts, the gladness and the joy.”
“Picture both these states: lament and weep for the sentence passed on sinners; mourn while you are doing this, frightened that you, too, may be among them. But rejoice and be glad at the blessings that await the righteous, and aspire to enjoy them and to be delivered from the torments of hell. See to it that you never forget these things, whether inside your cell or outside it. This will help you to escape thoughts that are defiling and harmful.”
 Nikodimos, St.. The Philokalia (Kindle Locations 903-914) Kindle Edition.