As the majority of us constantly struggle to appear physically beautiful, we are often forgetting the spiritual aspect of beauty. It's not that we do so by purpose, but that we are conditioned to do so (majority of the time).
From personal experiences, people repeatedly claim to notice inner beauty before outer, or prefer it. Is that the case? Yes, we do not want others to think we're shallow so we say this. However, outer beauty does matter to a certain extent. Don't get the wrong idea here! I'm not saying that what is presented in today's society is correct, but I hope you get the idea!

The complication with inner beauty is that, who is the superior being that defines good from wrong? One can ever so easily believe they are a beautiful being from within, on the contrary another wouldn't see them as spiritually beautiful due to diversity in morals, also considering how one is raised. Let me put it this way; if you are a religious character and follow the "proper ways of life" written by your religion, you will be considered beautiful and pure from another devotional person. Although, a skeptic, for example, would not see eye-to-eye and defiantly has their own descriptions of "what makes you a good person".
On that note, all I can do is suggest some ways to be open-minded and to find inner peace. I find that being happy plays a tremendous part in being beautiful from within.
No one can object that an open minded being has an advantage, and one who is at peace can find beauty in others (not only in people!) with ease.

. Some suggest meditating daily for at least 10 minutes to experience a better life style. Some poses are: Shavasana (corpse pose) = laying down back to the floor arms to the side. Lotus position= typical yoga pose, sitting down legs crossed. Being constantly stressed is an issue for most today. Even teenagers are experiencing high levels of this. It is important to free your mind and body in order to be free from stress and to be happy. Take the time needed to better yourself. Yoga will help to control your mind, being able to find true beauty in even the most unsightly things.

Be positive! Be happy! Be beautiful!
Sources:
http://www.wendydown.com/can-your-spirituality-make-you-beautiful
http://www.how-to-meditate.org/why-learn-to-meditate.htm/
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