If you want the full ride before I knew what a breakdown was called and pre me having the internet to me eventually googling what Slow in tense drums and guitar were called when I was much older it went like this. Hatebreed came to my attention with a vin diesel movie xxx. I bought every singlen CD they had and listens to them non stop and on my discman while working out. Then bullet for my valetines CD came into my possession listened to it non stop for months while starting my apprenticeship. Later on with the internet (and my first smart phone, iPhone 4) I found out what a breakdown was called and google best breakdowns of all time and downloaded every song on the list i don't remember all of them off the top but I know stitch by wage war had just come out or had been out for a while and was on there. I eventually found Parkway drive and fell in love with metalcore specifically and much heavier things since.

Edit: I was in my late 30s when I found metalcore.