You may have noticed that you do not worry while you are asleep. People can have anxiety based dreams, but generally speaking when the conscious mind closes down, so does thought. While we place the conscious mind on a pedestal, it is only the end point for subconscious drives, and all these drives derive in some way from the desire to survive. In fact the role for the conscious mind is simply that of navigating the external world so that we survive in an adequate manner. Think about it. Most of our daily activity is concerned with earning money, finding a mate, getting shelter and food, and striving to become part of a social group (safety in numbers). We may spend some of our time being entertained – cinema, opera, concerts, philosophy – and so on, but the majority of our daily actions are concerned with survival.
The reason we are such a successful species is that this waking consciousness is like an amplifier. Maybe we get fired resulting in cascading thoughts about paying the mortgage, and finding another job. Dozens of job applications, sleepless nights worrying about paying the bills, frantic activity until another job is found. This amplifier goes into overdrive, working out all the combinations of circumstances and finding potential solutions. A hungry dog on the other hand simply goes hunting, and if it fails to catch a rabbit it will just keep hunting until it either dies or successfully catches some prey. Its waking consciousness is far less developed and so it cannot amplify events in the hope of resolving them.
This amplifier, which we call our mind, is inherently anxious. The more it thinks about things the more energy it expends, more anxiety is created and resolution may or may not happen. The ideal solution is to police this monster in our heads and switch it off when we feel that thoughts are simply running away with themselves and serving no useful purpose. Obviously we cannot ignore the callings of the survival drive, but we can switch the mind off when further thought would serve no useful purpose. Meditation is useful in this respect, as is watching a movie, getting stoned – or whatever. The important thing to realize is that our mind is an anxiety machine designed to serve the needs of the survival drive. To live a reasonable life we need to learn to switch it off when it has served its purpose.