Watch your life. Marcus Aurelius 2.8

Watch yourself carefully. Feel your own movements—emotions, thoughts, intentions, regrets, reasons—and adjust the course of your expression accordingly. This is simple advice, yet still profound, especially when you consider how many of us spend time attempting to psychoanalyze others. Marcus might say that was time wasted, unless we used it to look inward, too. You can hear the Greek <here>.

Παρὰ μὲν τὸ μὴ ἐφιστάνειν, τί ἐν τῇ ἄλλου ψυχῇ γίνεται, οὐ ῥᾳδίως τις ὤφθη κακοδαιμονῶν· τοὺς δὲ τοῖς τῆς ἰδίας ψυχῆς κινήμασι μὴ παρακολουθοῦντας ἀνάγκη κακοδαιμονεῖν.

If we ignore the fact that we cannot understand what happens in another soul, still it is not easy for us to get a clear view of someone else suffering ill fortune. What is evident is that those who fail to attend the movements of their own soul must suffer badly.