For I want you to know how great a struggle I have for you and for those at Laodicea and for all who have not seen me face to face. (Col 2:1 ESV)

Paul is in prison and what is on his mind is not his own circumstances, suffering and hardship, but the struggle going on in the different churches and his desire to protect them from false teachers by sharing with them the riches of the mystery that is found in Christ so that they will be able to withstand heresy.