I first learned to do this in a test taking class in high school many moons ago. I later taught my children this as a way to relax. My daughter used it to fall asleep and to help her when her creativity has a momentary block. My son used it when his anger would get out of control. It help me survive their childhood with my sanity.
The first step is to get that comfortable spot. Some people sit up and some lie down. It is a personal preference. It always starts at your feet and tighten them as tight as you can and hold for 10 seconds then relax for 10 seconds. Move to your ankles and do the same thing flex for 10 seconds than relax for 10 seconds. Move up your legs to your bottom. That is a large muscle and will really help you to relax. Move up your abdomen and chest to your shoulders. Then you need to move down your arms. Always tighten for 10 then relax for 10. Finally you need to do your face than your scalp. That is where I start to do visualizations if I am going to.
Visualization is not my strong suit but I imagine a soft while glowing ball growing from the middle of my chest all the way out to my toes and fingers. I see the light heal any soreness and weakness I might have. It is my light so I can make it do what I want.
All of this take about 10-15 minutes and helps me feel very relaxed. It is a tool I am using frequency while I am working and going to school and raising children. It is a great tool for focus and does not require anything special except maybe some music. I have used Jeff Gold’s music to help with my exercise and to relax at night. He has a gift for the beauty that music can lend a relaxation technique.