Fiero is a Unique Emotion that is often seen after sporting events, but it's certainly not limited to athletic events alone. It is felt and seen after a difficult problem is overcome whether the obstacle is physical, emotional, intellectual, financial, etc. - and regardless of it's origin, once a significant problem is overcome and a great accomplishment is achieved, fiero is the name given to describe this emotion.
It is interesting that although English has more total words than any other language, it doesn't have as many words which describe the different positive emotions as many other languages. It needs more. The word "Fiero" is Italian in origin. In this photo Spanish Mountain Bike rider Jose Antonio Hermida Ramos, experiences fiero after winning the World Championship in 2010. The posture of arms up and moving wildly, fists clenched and jumping (Jose would be, but he's on his bike) are highly typical of fiero. Mr. Ramos' facial expression is also highly consistent - shouting, mouth open extra wide with teeth bared (including the bottom teeth) - interestingly similar to extreme anger - is demonstrated well after his victory. Note how his eyes are nearly closed as well. After a few seconds, just after the accomplishment is achieved, these very extreme facial expressions resembling pain and anger are replaced by classic emotional expressions of pure and extreme joy. It is here that you will see some of the most sincere examples of smiles and happiness.
Fiero does not need an audience. It is not braggadocio in nature. We all can recall moments when we felt fiero and we were alone - but like all positive emotions it is much more enjoyable when shared.