The Poetry Foundation has an interview with the American poet and memoirist Mary Karr, in which she discusses how the mind can be its own worst enemy:
If you’re suicidal, your mind is actually the keenest threat to your survival. Yet depressed people still listen intensely to their minds even though said minds NEVER have anything good to say. Think of it, you try to employ the diseased organ to cure itself! If someone outside your body were shouting those awful things you say to yourself in such times, you’d plug your ears and sing lalalala. You have to stop that mind or die.
A simple meditation practice I started twenty-three years ago involves counting my breaths one to ten over and over. Pure hell at first. I evolved through various practices—some Christian and Ignatian spiritual practices taught to me by a Franciscan nun and a few Jesuits along the way. I came back to breath last year. For me God is in the moment, and I tend to do everything I can to avoid being in such a stalled, unproductive place as the present. The ego has to stop inventing its reality and notice what’s actually going on, which process kills it (the ego) a little if you’re lucky.