My earliest F1 memory is a bit fuzzy, but I'm pretty sure it was the 90 Hungary GP. The first race I can say I really remember start to finish was the 91 Japanese GP, but I have some flashes from that whole season.
I had the fortune to be 7 years old when Senna got his third championship, and being Brazilian, I got the bug and went on following F1 closely up until 2012-2013. Endured Barrichello's comical lack of good luck trough it all, never expected Massa to get anywhere, and to me, Alonso and Hamilton are the best drivers I saw. My favorite seasons were 1999, 2003, 2005 (mainly due to the last hurrah of the V10), 2007 was crazy good and so 2008. 2009 was a bittersweet one because I really cheered for Barrichello and I think he had a great shot at the title that year. I also had the opportunity to go to both 2001 and 2011 Brazilian GPs: I'll never forget the V10 scream shaking my body down the main straight on friday!
2012 to 2013 came and I got bored with it, thought it was getting too much artificial and I simply couldn't handle Vettel being so successful (always thought he was an average to good driver) I never liked Schumacher, but I respected him and got a kick hoping to see his car braking and he defeated, but Vettel? Meh. So I simply stopped.
I've been trying to get back but I can watch a full Le Mans, any WEC race to be fair, WRC, freakin FE, any GT endurance race, obscure GT events, IMSA, old F1 races, Indy - would love to follow Nascar, but the ads bombardment really gets into my nerves - but I can't watch a full F1 race: either I get distracted by anything else or fall asleep (here, in Brazil, the races are pretty much always Sunday morning), so I don't know. Maybe I'll try again this season, but I feel I simply don't care about it.