Putting the word "fu" under your body is not the practice in Feng Shui. Folks often hang the word "fu" upside down, which means happiness.
Holding down the word "fu" is not holding down the blessing, you can't see the blessing.
In geomantic omen, auspicious ornaments should be placed in a conspicuous position, and unlucky things can be hidden or thrown away, just like dregs falling on the road and being run over by a car.