Motto for all future silence days (from some old lecture of mine):

Eat only when you are fasting
Be still while running
Speak only when in silence.

उपोषन्नेव भुञ्जीयात्
ब्रह्मचर्यमनुतिष्ठन्तावेव सङ्गच्छेताम्
तीव्रं धावन् स्थिर-शान्तस्तिष्ठेत्
मौनस्थ एव भाषेत

The second Sanskrit sutra here is left untranslated to keep it secret. Those who are true practitioners will find out and learn.

Many sadhakas say : I am anyway silent most of the day.
However, it is not silence if you are silent because you just happen to be alone!

Silence is silence when you have the intention, make the sankalpa, to keep a spiritual silence and then your mind is filled with spiritual contemplation and mantra, whether sitting, eating, bathing, lying down or running.