It is not a "must" to relax

In Christian theology again and again, for centuries it has been asked 'what do Angels do in heaven? ' This is an important question for people who are goal oriented... What do Angels do in heaven? Nothing is there to do! Somebody asked Meister Eckhart, "what do angels do in heaven?" He said "what type of a fool are you? Heaven is a place to celebrate. They don't do anything... They sing and they dance and they simply celebrate."

The 11th century mystic Tilopa says - "Do naught with the body but relax; shut firm the mouth and silent remain; empty your mind and think of naught"

So what does relaxation mean?

Relaxation is to be at home with yourself, at peace. How can you "trying" to relax, be at peace?

I was reading a book a few years ago. The title was "you must relax....!" I couldn't understand why this 'must' as the 'must' is 'against' relaxation? The moment we say 'must'.. then relaxation becomes an obsession. You have to... you must do this posture and lie down and suggest to your body from the toes to the head etc.. Why 'must'?