איזהו עשיר? השמח בחלקו - ללחום נגד העצבות, אפשר להבין את הפתגם ככה: אזוהי [דרך של] אושר? השמח בחלקו [של חברו] דווקא
So, what do we do when our lives seem miserable? Be happy about someone else's life. This is a very big secret to true happiness.
If you can look at your friend's life and see that things are going well for them, and you can take true joy in this, you can vanquish any depression, any sadness.
When we truly understand that our friends' and family's wellbeing is as important as our own, we can be happy even when our own lives are difficult.
[If the reverse is true, heaven forbid, we can't let our friends' or family's suffering get in the way of our happiness, because our own sadness could hinder our ability to help them in their time of need.]