"From now on let no one cause me trouble, for I bear on my body the marks of Jesus."
St. Paul's words of Galatians 6:17 are indeed mysterious in meaning and are interpreted differently by various people.
Some claim that the marks St. Paul bore in his flesh were the Stigmata or the manifestations of the bodily wounds, scars and pain in locations corresponding to the crucifixion wounds of Jesus Christ, such as the hands, wrists, and feet.
Stigmata is a term used in Christian mysticism to describe the manifestations of bodily wounds, scars and pain in locations corresponding to the crucifixion wounds of Jesus Christ, such as the hands, wrists, and feet.1 An individual bearing the wounds of stigmata is referred to as a stigmatist or a stigmatic.
The term originates from the line at the end of Saint Paul's Letter to the Galatians where he says, "I bear on my body the marks of Jesus." Stigmata is the plural of the Greek word στίγμα stigma, meaning a mark, tattoo, or brand such as might have been used for identification of an animal or slave.
Stigmata are primarily associated with the Roman Catholic faith. Many reported stigmatics are members of Catholic religious orders.2 St. Francis of Assisi was the first recorded stigmatic in Christian history. For over fifty years, St. Padre Pio of Pietrelcina of the Order of Friars Minor Capuchin reported stigmata which were studied by several 20th-century physicians. - Stigmata (Wikipedia)
Let us also recall that the Apostle Paul also says:
I am now rejoicing in my sufferings for your sake, and in my flesh I am completing what is lacking in Christ’s afflictions for the sake of his body, that is, the church." (Colossians 1:24)
Amongst many Catholics this interpretation is quite popular, but not the only one.
United States Conference of Catholic Bishops website has this to say about Galatians 6:17:
The marks of Jesus: Slaves were often branded by marks (stigmata) burned into their flesh to show to whom they belonged; so also were devotees of pagan gods. Paul implies that instead of outdated circumcision, his body bears the scars of his apostolic labors (2 Cor 11:22–31), such as floggings (Acts 16:22; 2 Cor 11:25) and stonings (Acts 14:19), that mark him as belonging to the Christ who suffered (cf. Rom 6:3; 2 Cor 4:10; Col 1:24) and will protect his own.
Take your pick as there is no one general consensus. As for myself, I believe that St. Paul bore in his flesh the marks of Jesus' crucifixion.
Other articles of interest: