ZombiesRunGame

It's been a while since I last used this site, and I know they've added a whole bunch of stuff since, but I absolutely loved it. It's basically a kind of a mix between an exercise app, a game and a radio play. It makes running a lot of fun. The story is entertaining, if slightly cheesy. Nothing too offputting. I like that you can listen to your own playlists in between.

I only wish they had something for cycling, now that I'm not running so much anymore.

Highly recommended for runners. I know they also have a beginner's app now, to reach your first 5K. Sounds pretty good.