I started running about 4 years ago for mental health benefits, and have kept it up off and on since then. Sometimes seriously, sometimes not.
I always run with an mp3 player, music can make a big difference to my performance, the right motivatory track at the right time can make the difference between taking a walk break and keeping going.
I've only done a couple of races, a 10k in Amsterdam (44.42) and a 10mile in the UK(1:26.16), I'm not particularly quick but the satisfaction is brilliant.
I started running more seriously again a month or so ago, I find it difficult to find complementary exercise. I normally just do press-ups and sit-ups after running. I don't like gyms.
I also just started doing walks with a weighted(17kg) rucksack for an event I may be doing next year, but I'm concerned about how bright an idea that is.