The interpretation of flying dreams can be dramatically opposite based on the context of situations in your waking life. Similar to some other symbols and metaphors, our subconscious uses flying as a metaphor to either encourage you or to warn you. This is why it is highly recommended that you keep a dream journal and get your dreams interpreted based on the journal and not just a single dream.
One of the interpretation of this dream is that you have found that freedom from some situations in your real life that had been bothering you in someway. It may be a situation, a relationship, job, health issue, emotional baggage or social strings. Dreams of flying can be very exhilarating and amazing but scary too. The emotions you experience during the dream will help clarify the situation is your waking life. The direction of your flight, upwards, downwards or sideways, can give deeper meaning to understand what your subconscious is trying to convey to you.
The other, and dramatically opposite, interpretation is that your subconscious is telling you that you are or have taken up something that is beyond your capability and you are most likely to fail at it. The context, again, can be explained by what you see in the dream. Are you flying alone or with someone else? Is the surrounding familiar?
Dreams of flying can sometimes be what is categorized as lucid dreaming where the dreamer (you) is in control of the dream. To listen to the hidden message of your subconscious, it is advisable that you let the dream unfold by itself instead of you trying to control the dream.