Close your eyes and imagine an endless blue sky underneath your eyelids.
When your mind begins to think, for example, "I wish I was sitting on the beach with this blue sky instead of in my bedroom", see the thought on a puffy white cloud and watch it float through the sky.
When your mind asks, "Should this puffy white cloud be big or small?", label that as a thought and put it on another cloud. Watch that cloud float along.
Judith Hanson Lasater said in her restorative yoga trainin that we shouldn't worry about how our mind keeps on thinking when we try to meditate.
She said that thinking is the brain's job. Just as you can't ask your skin not to sweat, or your lungs not to breathe, asking your brain not to think is impossible.
The key is to not grab onto the thoughts. The key is to watch them for what they are, only thoughts. They are not you.
You are the blue sky.