Wrong. That is not the corpse pose. Lying flat on your back and relaxing every muscle in your body consciously is difficult for most. If you are in a group session, then you can fake it. But you won't get far with the purpose of Hatha Yoga that way.
The corpse pose is very internal. It is the precursor to meditation. So if you are rushed through it without even enough time to day dream for a few moments, practicing it every moment you can alone will bring results.
What It Does for You
As you gain more control over your body's different muscles by relaxing them, you are slipping away from the more manic pursuits of our diseased culture. You can be in it while not being of it when you master the corpse pose. You will find it easier to be in a witness state despite what is going on around you.
Eventually, this leads to feeling more centered and more grounded in this worldly realm, because you are! You can't be in the now if part of you is hither and another part dither.
The corpse pose aligns your subtle body with your physical. The subtle body is your energy field. This body remains even after the physical body expires. Then it is known as your astral body. It is what you will be taking with you! So the corpse pose is more important than many who practice or even teach Hatha Yoga realize.
Letting Go is What it's All About
Ultimately, your experience is the the final judge of how well you do the corpse pose. You should practice on a firm surface with minimal padding at first, leading to no creature comforts eventually. Flat on your back, legs apart slightly and arms slightly apart from your body with palms up. Palms up helps you stay awake.
Falling asleep is avoided. You want more consciousness, not less. At the same time, a mind racing or drifting is distracting. When your mind does this, bring it back gently to one of two physical areas: breathing or relaxing tense muscles.
The standard technique of releasing tension in sequence from the feet up or from the head, neck, and shoulders down takes time. So you may have to be satisfied with partial relaxation sessions as you progress toward total relaxation.
As you progress, sometimes relaxed muscles tense up again. Go back to that section and continue until you feel the tension release again.
If the orderly sequence of conscious relaxation in different muscle sections is too difficult, then simply focus on your breathing in a relaxed manner. When your breathing is relaxed and even and you are only observing it, allow your awareness of an obvious area of tension. Stay with it until it the tension releases. Then shift your awareness to another part that is tense.
As you continue in this way, tensions previously unknown may offer themselves to you for release. In other words, there are tensions that are unconscious. By releasing them, you are releasing consciousness.
Just Do It
The corpse pose can be practiced often, separately and alone. A safe, quiet space is paramount. Some soothing music that suits you is beneficial if it isn't distracting. At first you may feel dull and tired, or restless and wanting to move about. These symptoms dissolve with patient practice.
Stress is the source of many health problems, mental and physical. The corpse pose can be your relief from stress, and allow you to regenerate energy with less sleep. But it's so simple it's hard, at first.