Check out this post from Desiring God:
Richard Baxter has taught me more about the art of meditation than anyone else. He was a Puritan who lived during the 17th century. Baxter suffered chronically from kidney stones, headaches, bleeding, toothaches, swollen feet, and a myriad of other chronic ailments. Yet God used him mightily to evangelize almost an entire town, Kidderminster, England. The city consisted of over 2,000 adults, plus children.
In The Saints’ Everlasting Rest, Baxter states that, because man is a rational creature, we must reason with ourselves. We are to take a truth and mull it over in our minds. He compares it to a balance that sits before us. There is a natural desire to want to tip it, to add a little more weight, and then a little more, and then a little more, and finally the thing tips. So, it is to be with our hearts. We meditate upon a truth and add reason upon reason in order to believe this truth, to revel in this truth, to delight in this truth, and eventually the scale tips. We bring one reason to bear, and then another, arguing with ourselves, until eventually we are affected.
Read the whole article here.