Grew up in Ann Arbor with season UM football tickets, so there was no way around it. My dad went to every home game from 1967-2007 except for 3 (one when his father passed that morning, two when he was out of town for work). As he's gotten into his 60s, he's lost the desire to sit through adverse weather, so I'm sure he's missed more per season since then than he missed for those 40 years combined.
I started showing an interest when it was on TV in 1990. My dad tried to capitalize on that and take me to a Michigan-Maryland game that year, when I was 6. Watching casually on tv, when you can leave and play and circle back was very different than going. Apparently he bought me a personal pizza, a McDonald's meal, and an ice cream just to get me to the 3rd quarter, before he pulled the plug. He waited two more years before trying again for Michigan-Iowa in 1992, and by then I was totally hooked. I went to every home game from 1992 until I went away to college in 2002, unless I had my own sporting event conflict, probably the most famous being the 1994 Kordell Stewart Hail Mary, although the most fun I ever had was the '97 Big Ten title clincher against OSU (although '95 is close).
I always thought the student section looked like so much fun, so when I enrolled at Indiana, I also got season tickets, for $30. That's not one of those "back in my day, everything cost a nickel" type stories. That was insanely cheap even in 2002. But the experience was worth basically $5 per game, so it made sense. When I transferred to MSU for my sophomore year, I didn't get student tickets. I figured I could get on board with cheering for a neutral Big Ten team like Indiana, but I wasn't going to pay money to go "cheer" for a rival like MSU. It would be a waste of money. By junior year I had so thoroughly enjoyed my experience, that I was legitimately rooting for MSU whenever they played anyone but UM. I went home for the UM-MSU game that year. That was the Braylon game, where UM overcame a 27-10 deficit midway through the 4th, after Stanton got injured, and won in 3OT. I wore UM stuff to the game, but my heart wasn't in it. That was the last time I even thought I was rooting for UM.
I remember in 1991 (2nd grade) we had a morning journal prompt every morning. My parents saved one where the question was "What is your favorite TV show, and why?" My 7 year old answer? Michigan Replay with Gary Moeller. I guess I was hooked already.