It's not impossible. I just haven't tried yet.
Arete is the first circle of Magic that the Awakened come to grasp: the ability to do the impossible. The art of Arete is part instinct and part skill,
Arete is flexible - nearly any action that the Awakened can take can channel Arete to achieve wonders. Running, speaking or swinging a swords can all be performed as a legend would. Different skills or actions require different training and an Awakened's Arete is influenced to a high degree by their Narratives: a great swordsman would find the Arete for public speaking outside their grasp. Some manage to change their Narratives and learn new Arete, like a wandering swordsman becoming a leader.
The magnitude of Arete varies with the skill and the power of the persons Narrative. An Arete wielded by an Awakened possessing a strong narrative and experience can do far more than an inexperienced or weakly-enforced Awakened.
At the absolute peak, Arete allows an Awakened to do things like leap many times their own height, outrun wild animals, clip the wing off a fly with a thrown pebble and similar feats.
While Arete can enable deeds that will turn into legend, there are limits. The Dreaming-World displays a preference for effort and tenacity in its impossibilities; it will not allow the Awakened to clear a mountain with a single leap but climbing it with nothing but her bare hands, it will. Additionally, Arete never displays overt supernatural elements such as shapeshifting, conjuring flames or lightning, or other such phenomena.
Cost & Consequence
The use of Arete relies on the Awakened's endurance and personal reserves. It is more spiritual than about sheer physical fitness, with practice and narrative reinforcement making it easier and less straining. The less impossible the action, the less straining it is though the Awakened almost always have an narrative of remarkable second wind and resurgence - especially when the situation seem at its most dire state.
Legends of Excellence
Arete gains in power as its narrative is strengthened. As an Awakened practices her archery every day, she reinforces her narrative as a skilled archer - in addition to keeping her mundane skills sharp. Others might meditate to sharpen their technique or imbibe forbidden droughts to strengthen their bodies: there are many ways for the Awakened to empower their Arete.
There are two principle ways of empowering the Narrative as it relates: Immediate and Essence.
Techniques that are done in the moment. They provide short-term boosts to the Narrative and range from drinking a potion, visualization or more esoteric techniques. These take anything from a few moments to a few hours to perform and their benefits are expended as soon as the action is taken.
The ritual, stance and breathing technique of a swords-master just before her lighting draw and strike is an example of a typical Immediate technique.
Essence is not a technique, but relate to the way the Awakened live. The martial artist who practices every day without rest, the mystic who seeks the harshest elements to meditate in or the doctor who's experiments blur the lines between life and death, who lives or dies.
Many Awakened instinctively practice Essence - it is just who they are. The discipline and training required to master a martial arts is an example of an Essence technique.
The two paths are often combined. Either can incorporate an element of risk, danger or side-effect and these serve to make the narrative stronger at the cost related. The alchemist's strengthening droughts might only last for a certain duration or destroy the body if taken too frequently - these sort of drawbacks are common with the more esoteric and powerful Arete techniques.