I'm too much of a dilettante to get serious about any hobbies. At this point in my life I've noticed a pattern where I am obsessed with something for a brief period of time, varying from weeks to months, learning all I can about it, then once I reach some level of understanding I am no longer interested. This has actually prevented me from even starting some hobbies, including RC helicopters (so far), home machine tools (lathe, milling machine, etc.), home theater, etc. Any hobby I have devoted serious time to, I have always languished in the novice stage. Of course the advanced stages are what draw you in; getting an instrument rating instead of just flying VFR, actually practicing several hours every day to become reasonably proficient with guitar, or enduring enough trial and error cycles to build a working wooden clock.
Radio control- This was my first "real" hobby. From about age 13 to 18 I enjoyed fixing and racing them, but never went off the deep end with it.
Guitar- This was in my late teen years, and I got a bass guitar to start a band with some friends. We mashed our way through some Metallica songs, but not much beyond that. Another friend of mine, who is a professional musician, kept me motivated and I even had him give me lessons, but I guess just didn't want it badly enough to practice. I kept dabbling into my mid 20's, and havent really touched it in 7 or 8 years now.
Clock building- I spent about 5 months designing one with Solidworks, and a few months thereafter cutting the gears and assembling my design. I eventually got something that ticked which was exciting, but I haven't revisited it. Maybe I will resume this when I have the space for a workshop again.
Flying- I've always been interested in aviation, having an uncle who was in the air force talking about his flying all over the world. I eventually decided on flying lessons and actually stuck with it to get my private pilot certificate. Ive accumulated about 170 hours so far, but never did any of the long overnight or multi day trips I thought I would. My longest flight is still the multi leg trip that was part of my student training. I joined a club and thought being around other more accomplished pilots would bring me up, but that didn't happen. It's now been about 18 months since I last flew. Partially because my wife and I had a kid in that time, but my flying was very infrequent long before that. Again, this is something I still have in my pocket to revisit later in life.