Fear and worry are born of the imaginings of a mind that is influenced by wordly conditions. They are rooted in craving and attachment. In fact, life is like a motion picture in which everything is constantly moving and changing. Nothing in this world is permanent or still. Those who are youthful and strong have fear of dying young. Those who are old and suffering worry about living too long. Locked in between are those who craze for merriment all the year round.
Joyful expectations of the pleasant seem to pass off too quickly. Fearful expectations of the unpleasant create anxieties that do not seem to go away. Such feelings are natural. Such up and downs of life play with an illusionary self or ego like puppets on a string. But the mind is supreme unto itself.
The training of the mind, otherwise known as mental culture, is the first step towards taming mental unrest.
Venerable K. Sri Dhammananda, Problems and Responsibilities