It must be a primal instinct. Music. The rhythm, sound, melody and all other aspects can influence how you feel, and deeply. I think only love is like it as far as the affect it has on your soul.
I make music mostly to try to communicate thoughts and feelings that course through my brain. I'm a thinker - nothing too deep (like studying philosophy) but since I've been a computer programmer for 41 years, I do like the logic in philosophy.
I absolutely love learning how things work. Mechanical, Electrical and the most complex of all, human things. Music has a logic but is much more human than mechanical or electrical things.
I also love the romance of history and definitely am an "old soul". I love old things that evoke feelings and moods and spark imagination. Rust and cracked old composite things and paint patina to me are things of great beauty and which have soul. Very few things in life have soul, but when you stumble on one of these, you just know it.
My reentry into playing music and writing songs - after being away for 30 years has just reached the point where I can easily take an idea or vision and set it to sound. I'm not the best musician, but in the last two years since picking this up again, I have grown greatly and I'm very pleased and proud of that. My guitar, bass and keyboard skills have improved noticeably. Learning Cello has been addicting and in November it will be one year playing that. My lap steel, dulcimer, mandolin and violin skills are very basic, but I find that those instruments are secondary to my main musical interests.
I suck as a singer, but while I will never be known as a song writer / singer or artist, attempting to sing is really important. Some of the best tin pan alley song writers couldn't sing if their life depended on it. I have heard covers of songs that were better than the original. Some famous artists are pretty poor singers but exude feeling and emotion that makes up for it. Examples include Jonathan Richman, Dylan or Jeff Mangam from Neutral Milk Hotel. I'm trying to suck as bad as their singing! My dream would be that a decent band or artist would take my song idea and make it great.
Music, every single day has always (and now even more so) been a very important part of my life.