All creative people develop the skill of entering the landscape of their imagination. If you've ever been hypnotized, it's a similar experience, and it's very simple to do. The process is just like a daydream. You can even do it with your eyes open.
Imagine that you’re walking down a staircase, or descending in an elevator. When the elevator stops, you open a door into a landscape --- a beautiful garden, or a mountain meadow. Start wandering through this landscape. Make it real: smell the flowers, feel the wind, listen to the waterfall, or to the sounds of chirping birds.
Or, imagine that you're floating, on a magic carpet, or on a cloud, or in hot-air balloon. Imagine that you're drifting over landscapes. When the carpet lands, you can wander through the landscapes of your imagination.
You can stay in your imaginary landscape as long as you like. Even two minutes will refresh you, and will feed your writing. This technique is a stress-reliever par excellence.