From my tutor: not to become a Green or Blue supporter at the races, or side with the Lights or Heavies in the amphitheater; to tolerate pain and feel few needs; to work with my own hands and mind my own business; to be deaf to malicious gossip.
We do not know who Marcus’s tutor was, but he was probably an educated slave.
He gave good advice.
Green and Blue were chariots racing teams; lights and heavies were types of gladiators. Marcus believed in physical fitness, but he didn’t have much time for spectator sports. Why watch what you should do?