About a year and a half ago, aged 36.
And I’m still crap.
I got my first one for christmas in 1971 at the age of twelve. I bought a schwinn 24" that summer and started doing my paper route with it. I then started picking up the neighborhood kids and gave them rides on my shoulders. Talk about a moms freakin out! Ha! I even went to the circus and bought an 8’ uni. I used to lean it against the gutter on the garage and then climbed a ladder and got on the roof to get on it. After a couple years of semi regular riding I put it away and took it out once or twice a year. About six months ago I saw some unicyclist on youtube and was shocked. You young guys are sooooo talented. I then broke out the old schwinn and got back at it. In the last 6 months I bought a 26" torker, a 20" sun, and a 36" nimbus. I am 48 now and am hooked for life! This is great exercise and there is so much diversity as to what you can do on them.
like when i was 10
Daaaam some of you guys have been at it for a while. I’ve been unicycling for about 5 months but had to take a month off due to a concussion.
Last feb I first ever tried one. I didn’t know how I would ever learn, but I did. Now 9months later I am sif’in up 20" ledges with no prehop and doing the occasional 180 if a picnic table top.
OUCHIES!!! 
I’ve been riding for sometime now. I’ve had 4-6 unicycles since then. 
summer 2003 i got a torker cx 20" i rode to school and just around for a while. I was kidding when i asked for it for my bday but i got the bug. I sold that and upgraded to the 24". I still have the 24" but it now has a bent rim as I started actually getting into serous riding this summer. I mostly ride Muni on my dx 24" and have gotten so many other people hooked.
I bought my first uni 2 years ago (not sure why, just something different to do), tried for a bit but lost interest (didn’t know this site existed, didn’t know about MUni or any of the really cool stuff going on here). 6 months ago I found this site and thought I would give it another go, it stuck and I got totally hooked!
I started when I was (and still am) 17 years old.
I started because I am into juggling, and every time I went to youtube to watch juggling videos, I always seemed to some how find some unicycling videos, and I watched them. 
Also most of the juggling shops on the internet have some cheep unicycles for sale, so that also sparked my interest. So I got one, and have been riding ever since. 
learnt to ride last year at school (circus skills workshop, the uni was the only thing that was appealing to me)
got first uni this april, now have a second…
i started last christmas when i got my first learner uni and i have been at it ever since. im celebrating one year of riding by getting a nimbus trials uni this christmas
I was 17 at uni (haha). An engineer friend had a home made one, which he lent me. I used to it get around campus for the better part of a year before giving it back.
I hardly rode a unicycle at all for a gap of nearly 25 years, but I was a keen road bicyclist / commuter for all of that time. October last year saw me unemployed for a while. Having heaps of time on my hands, I thought to myself, “Hmmm. What to do… - I know!- ride a unicycle again!” - so I ordered a nasty 24" Chinese machine from ebay. Then I sniffed around the net, wondering what had happened to unicycling in 25 years, and wow, A whole lot had happened! 25 years ago, we thought we were pretty cool jumping gutters and riding down a couple of steps. Things had been taken to another level! - So with renewed enthusiam, I started riding, and bent the nasty cheap uni pretty bad after 2 weeks from doing drops. Since then, I have managed to acquire a Nimbus 24" Muni, a Nimbus X24 (sexy all black with hookworm) and the current love of my life, the KH29 (with 2.55 Weirwolf and sealed JimiC Mags) which I commute on daily. If I don’t ride at all for more than 1 day, I get withdrawal symptoms!
I started when I was 50. I chose unicycling for my middle-age crisis because it was cheaper than a hand-made Italian sports car.
i tought myself how to ride in the fall of 2005. (wow two years already!) i have never gone more than 4 weeks w/o riding since the day i bought my uni. I also have givven up almost everything else i did before uni’ing besides swimming (video games, soccer, reading a lot)
Yeah go swimming. It’s the only sport I do right now besides Uniing