It is estimated that we have approximately sixty thousand thoughts in a one day period.Many are random, but for some there are strong patterns which influence  behavior. If the thoughts are mostly negative then to some degree they will influence the choices we make . One way to balance this is to learn to substitute some positive thoughts at the times when we are most susceptible to having control of the patterns. Before we go to sleep,, and when we wake it is worthwhile to gently meditate on some positive thoughts about the coming day.