Stanford psychology professor Benoit Monin has done a study that shows people overestimate how happy their friends are (in part, thanks to Facebook), and thus feel worse about their own lives.
-- Pay more attention to silent majorities. A handful of frequently posting online friends can overshadow the fact that hundreds had nothing fun to report and thus remain silent.
-- Filter out toxic others. By being attentive to your feelings, you may come to realize that you often feel down after reading posts from specific online friends who tend to play up how fun their life is. You may want to block their posts and only check their wall when you are having a particularly good day.