I wrote a comment on deviantART and realized it's worth blogging here. It is based on a picture I have in my wallpaper slideshow for a long time because it impressed me so much on a deep level:

http://moderatelydeviant.deviantart.com/art/Against-All-Odds-285429361

Twilight shows maybe the clearest example of the power of the controlling mind trying to force its way, fueled by negative emotion. Her energy shoots at Discord, but you see it strike her friends, too, mostly from Discord's head. True friendship empowers love and comes from the heart, while in this picture Discord is like an inner demon of Twilight, and her mental struggle with it gives it power and causes discord in her friendship, turning her friends against her and her against her friends.
The solution to this problem was eventually portrayed beautifully in her battle against Tirek when she allowed herself defeat and let her heart lead the way, against all conceptual fears.

Also, Pinkie has a duck in her hair.

UPDATE 2015-12-02:
While watching the season 5 finale, my desktop wallpaper switched to this. The finale is another reminder of this recurring message that more or less is in all MLP episodes and I appreciate it greatly. It is something worth moving towards, regardless of how little success we might experience at first.
Friendship brings together, because true friendship is fueled by love. And love is magic. Friendship comes from the heart and is empowered by it.