In order to have peace of mind, prepare yourself in advance to accept with serenity whatever occurs. People who expect everything to go the way they want are caught off balance by difficult life situations. Have an awareness that difficulties constantly arise. Being prepared in advance to accept what happens makes it much easier to cope with the vicissitudes of life.
When you feel anxiety about a future event, imagine the worst and accept it. This has a very calming effect… at worst, the future will be familiar and, at best, it will be better than you had expected it to be.