I know a few people have mentioned the Zombies, Run! App (its on the Android now too I believe). It encourages you to run, by giving you a story for each of your runs, along with Zombies occasionally breathing down your neck to make you run faster.
I got the App last summer, and it got me out more, but I wasn't running that much because I'm not that good a runner (in fact I've always been rubbish).
Anyhow, they now have a c25K App (about £2.99), which I've just started to use. I had tried the free NHS c25k podcasts in the past, but actually struggled to run for 60 seconds. In the zombie one you just start by running for 15 seconds, which I found far more manageable. I've so far done my first two work outs (10 minute walking, then 10 lots of 15 second run followed by 1 minute walking, followed by 10 minutes free run - where you walk and run as you feel like).
My DDs are acting as my own personal trainers and dragging me out for a run even when it my rest day. My eldest DD listens to it on her iPad, but she is pretty fit already so she just makes the runs more intense.
The biggest draw back is that it doesn't know when you are running up hill, which is an issue near me!