The Whole Brain

There is increasingly more evidence that musicians have organizationally and functionally different brains compared to non-musicians, especially in the areas of the brain used in processing and playing music; if you learn how to play an instrument, the parts of your brain that control motor skills, e.g., using your hands, running, swimming, balancing, etc., hearing, storing audio information, and memory, actually grow and become more active.
There is also evidence to show that both listening to music or playing a keyboard instrument gets the entire brain working (photo), increases memory capacity, and can improve spatial-temporal abilities over the long term; it also refines someone's sense of time management and organizational skills and teaches perseverance.
A good musician knows that the quality of practice time is more important than the quantity; in order for you to progress more quickly, you learn how to manage your practice time efficiently; the majority of musicians have to work difficult sections of music multiple times in a row before they can play it correctly; it takes time and effort and a steadfast determination to persist in spite of counter influences [See blog, The Lizard Brain, Parts I-VII, The Book].
Playing a keyboard instrument enhances coordination; by reading notes on a page, your brain subconsciously must convert those notes into specific motor patterns while adding rhythm to the mix.
Music involves constant reading and comprehension; when you as an organist see black and white musical notation on a page, your brain learns to recognize what the note names are and translate that into a finger and/or foot position; at the same time your brain reads what rhythms the notes are arranged in; all of this helps to display superior cognitive performance in reading skills.
Playing a keyboard instrument also teaches responsibility; first and foremost is protecting your instrument from damage and keeping it in good working condition; other important aspects are remembering musical events, preparing your material in advance, scheduling time for practice, and getting you and your instrument there when the time comes.
If these were the only benefits, it would be plenty; but, there's more ...
It exposes you to cultural history, sharpens your concentration, fosters your self-expression, and relieves stress; it creates a sense of achievement, promotes social and listening skills, and teaches discipline.
Oftentimes music reflects the environment and times of its creation; music itself is history, and each piece usually has its own background and storyline that can further your appreciation of other cultures.
It requires you to concentrate on things like pitch, rhythm, tempo, note durations, and quality of sound; group performance involves even more concentration because you're needing to hear everyone else and play in harmony with them.
Since it's your instrument, you can play whatever you want on it; a musician can play something with emotion, just like a painter can paint their emotions on a canvas; this has been proven to relieve stress and can be a great form of therapy.
Overcoming musical challenges that you thought you could never quite master can give you confidence and a great sense of pride about yourself; the friends you make through your musical work become like family; by playing a keyboard instrument, you're guaranteed to improve your listening skills; the best musicians in the world are masters of discipline.
It doesn't stop there; there's even more benefits ...
One of the goals of practicing so much on your instrument is so you can perform for others; the more you get up in front of people and perform, the more you'll reduce any stage fright; it becomes much easier to get up and play for a crowd, the more you do it; it also promotes happiness in the life of the player and the people around them; in addition, depending upon what's being played, it can have positive effects on faith (Rom. 19:17), causing it to rise [See blog, Hymns, Parts I-V].
Team skills are a very important aspect of being successful in life; playing a keyboard instrument, at times, also requires you to work with others [instrumental soloists, vocalists, or groups of them] to make music, to listen to them as they perform, and to cooperate with the people around you.
A very convincing argument can be made therefore, to keep on practicing at the keys and to always hold music in high esteem, to always think about the end results and remind ourselves of all the great reasons that we love to play.