”And Hashem said to Moses: Come up to Me on the mountain and be there…” Exodus 24:12
R’ Menachem Mendel of Kotzk observed that if Moses was going up to the mountain – of course he’d be there!
Perhaps not! A person may be somewhere physically, but they may not be fully present. They could be playing with their kids, visiting someone in the hospital or in a synagogue praying, but distracted with their minds elsewhere.
“You are where your thoughts are” – Rabbi Yisroel Baal Shem Tov