I'm 41. I suppose I started
I'm 41. I suppose I started running in my early 20s, but that was as part of a "commando" training course my dad and I decided to do in our spare time. After that, and from then until my mid-30s, I followed a pattern of abstaining from exercise for 9 months, followed by attempting to start running again for 3 months. In 2004 I joined a new gym and used it heavily for 6 months, combined that with running, and planned to enter a half-marathon the following March. Well, on New Year's Eve 2004, my daughter was born and all that went to sh*t! Eventually, IIRC in mid-2007, I decided to start running again, and haven't really stopped since then, although progress has been slow.
I started running minimal / BF a few months ago, partly just for something new to try, and I'm still trying it.