John tells us that he was in the Spirit on the
Lord's day in Revelation 1:10

This shows us that when God reveals Himself
to His people, He does it when they are in the
spirit.

On Patmos, John speaks of himself as "your
brother and companion in tribulation". There
weren't many comforts and his only consola-
tion came from communing with God. That's
how he happened to be the Spirit on the Lord's
day.