Sōphroneō (G4993) means to be of sound mind, sober-minded, or to exercise self-control and sound judgment. From sōs (safe/sound) + phrēn (mind), it describes the mind functioning as it was designed — clear, disciplined, and rightly oriented.
Romans 12:3 uses the cognate sōphroneo to mean 'think with sober judgment' in contrast to pride. 2 Timothy 1:7 declares that God has given us a spirit of power, love, and a sound mind (sōphronismos). The antidote to anxiety, delusion, and pride is the sound, Spirit-formed mind. Titus makes sōphrosunē (self-control/sound-mindedness) a fundamental virtue for every age group in the church.