I'm 40 something, (almost 50) and I've been building and flying for eight or nine years now. I'm also an instructor pilot for a local youth organization, The Hawks R/C Junior Aviators. When we're not flying, which is almost half of the year, I run building workshops on Saturdays. I really love teaching kids how to fly because I get the added benefit of becoming a better pilot. I believe that the best way to learn something is to teach it.
I currently have three building projects going. I'm building a BUSA 1/4 scale Sopwith Pup, A GP Patriot XL, and an Ultimate 10-300. I'm also assembling a SIG CAP 231 EX, so you can see that I don't have a problem with ARFs. In my workshops, we're assembling an H9 Pulse XT (40 size), so I guess technically speaking, I'm working on 5 planes at once.