During the “Sermon on the Mount,” what did Jesus mean by the words “take no thought for the morrow  (Mt 6:34)?

Jesus actually answered this question in the rest of the verse. Notice what He says. “For the morrow shall take thought for the things of itself: Sufficient for the day is its own trouble” In other words, today has enough problems to be concerned over without worrying about tomorrow.

The point Jesus was making was not that a Christian should adopt an attitude of apathy or laziness as a way of life (see: 2Th 3:10), but rather that worry is totally unnecessary for those who are cared for by God the Father.