In reply to Firestarter:
I am 50 too, nearly 51, and have been running, off and on, for several years. For a couple of years I stopped and found that my weight climbed several kg until I was well overweight. Then I started running again, eighteen months ago, and have not stopped since.
The way I got going again was to set the barrier really low. No watches, no targets, no busy training schedules, they can come later. Just get out and plod, preferably somewhere nice. In fact, my mantra, in my head, as I went along was "just plod on", which is a habit I am trying to get out of now but which was useful then. Actually, there was one target, which was to keep it up for years. Mick is right about the danger of getting too obsessive too quickly and burning out. I wanted it to be for the long haul.
I also recorded what I did, because for me it helps to see the miles and the runs pile up. I mixed the running up with a lot of swimming and some cycling, all of which helped me to lose weight, which I did, dramatically for the first few months and have continued to do more slowly thereafter. I recorded my weight weekly. The graph that showed its decline was a strong motivator to continue. Another thing that helped was to make the running part of the day, rather than an onerous extra. So, I would run from work and meet my wife on her way home. That doesn't work so well now, but it was useful at the start.
It hasn't been too bad with injuries. Mixing the activities has probably helped, as has being careful about how many miles I run in each pair of shoes - although I run quite a lot, 800 or so before I change, which seems to be OK. But, it does hurt. My backside ached for months at the beginning, and I ached all over when I first combined the running and the swimming. But you learn to distinguish discomfort from injury, and live with it. It's better than being fat and unfit.
A further help once I had got going has been to set some targets. For me, these were not detailed, training plan type targets, but a few specific to-do list goals, which for me were the Welsh 3000s, or the Bob Graham Round, or an Ultra. Then I started posting on Fit Club, which helped me take things to another level amid an encouraging and tolerant group. Others might find an actual club more useful, but I don't want the time commitment in an already busy life, so haven't done that.
The other thing that has helped me is a mental outlook I have used in the past when I have learned languages. Nothing works without hard work, the rest is detail and cannot make much of a difference without the hours and hours of effort over a sustained time span. So, don't fret for too long about what to do, or worry about how you sound amid the bilingual types, just get out there, start gently, somehow, and keep going.