Don't let your imagination to be crushed by life as a whole. Don't try to pictures everything bad that could possibly happen. Stick with the situation at hand. ...Then remind yourself that past and present have no power over you. Only the present.
Marcus AureliusDo not disturb yourself by picturing your life as a whole; do not assemble in your mind the many and varied troubles which have come to you in the past and will come again in the future, but ask yourself with regard to every present difficulty: 'What is there in this that is unbearable and beyond endurance?'
Marcus Aurelius