This is a How-to with lots of pictures to make it easy. Start with simply sleeping on your back.
or on your side.
Consider using the top flap of the box as a pillow.
If you are longhaired, use the benefit of your coat and tail.
Remember that you and your box must nearly become one.
Use your imagination: try an S-like position.
or an inverted C-like position...
or even an L-like one.
If you totally trust your humans, relax your back legs to the maximum.
Sometimes O-like positions do not fit the box well, but you can always experiment.
If the box is rather small, try sticking your paws & tail out of it...
or stretch just one paw out, like this (back paw).
or like this (front paw).
Invite your friend to join you.
and enjoy it.
Your humans may wonder how you can sleep like that.
ignore them and enjoy..
Perhaps they will not even notice you.
To avoid unwanted attention, choose a box that matches your fur color. or you can trying hide in an absolutely unexpected box.
This position is for experienced yoga cats.
as well as this one.
Even small boxes will do in a pinch.
You can use any box-like structure you can find to get some practice.
Just remember to be creative!
There are two means of refuge from the miseries of life
Music and cats - Albert Schweitzer