Whether you are interested in reaching samadhi or plan to ignore Yoga entirely, I would advise you to remember at least this one Sutra.... In my own experience, this Sutra became my guiding light to keep my mind serene always.
What are those four locks? The happy people, unhappy people, the virtuous and the wicked.
Happy people - By that jealousy, you will not disturb her, but you disturb your own serenity. Make that person your friend.
Unhappy people - Have compassion. If you can lend a helping hand, do it. Be merciful always. By doing that you will retain the peace and poise of your mind.
Virtuous people - Don't envy him; don't try to pull him down. Appreciate the virtuous qualities in him and try to cultivate them in your own life.
Wicked people - So, what should be our attitude? Indifference. "Well, some people are like that. Probably I was like that yesterday. Am I not a better person now? She will probably be all right tomorrow." Don't try to advise such people because wicked people seldom take advice. If you try to advise them you will lose your peace.
If you use the right key with the right person you will retain your peace. Nothing in the world can upset you then. Remember, our goal is to keep a serene mind.
Update: At the Yoga Sutras discussion group, we had a very interesting conversation about this Sutra. The one piece I would like to share is the exchange around the word indifference. Another word we contemplated was equanimity. Does the change in word choice change your experience of the sutra? Make it seem more or less possible to live out in your life? We also discussed how being even-keeled could make us more effective at addressing injustice. Food for thought I wanted to share here.