The purpose of a mitzva in repairing the world is fulfilled specifically when the person executing the mitzva performs an action with his body.
Therefore, when a mitzva is not performed through action, it is not truly a mitzva.
As was stated, the purpose of mitzvot and of man is to bring divine light into the lower world.
The more the mitzva descends into the physical realm, the more it fulfills its purpose and perfects itself.
In the upper, spiritual worlds, there is only a very limited expression of a mitzva, an illumination or a spark of its being.
Only in the lower, material world can a mitzva be fully manifest.
Rabbi Adin Steinsaltz