I was 8 and there was an acoustic guitar at home, all I wanted was to rock my fucking brains out, but I didn't know shit, so, I took a guitar course at school, but I hated it, I didn't want to play those pussy songs with basic chords... I wanted to rock right away, I wanted to learn the chords and how to play ROCK, so, after 3 classes, I quit.
Got myself some crappy GNR songbooks, you know, those basic things with the chords and the lyrics... acoustic songs sounded better of course, things like wttj or scom were way ahead of my skills and an acoustic guitar didn't help much either. I kept playing though, I learned the chords and could play well enough (no solos or crazy shit). Then I got my 1st electric guitar, and my mom regretted she gave it to me for my birthday, I wouldn't stop playing, now I could play the way I wanted, with the Gain knob on 10 in the amp playing GNR and Nirvana non-stop.
Well, I've never stopped since then, never took classes (other than those shitty 3 classes when I was 8), I'm self taught. Now I have a few guitars and basses and I've made music a part of my life, there's never a bad moment to grab the guitar and play. If I'm sad, upset or frustrated, or happy, playing guitar or any instrument is a cathartic experience. Kinda same story for bass and piano, self taught too, learned later though, but I love them as well, although guitars will always be my favourite babies.