Running is addictive, and can if you let it take over your life. Of course some people have more of an addictive personality, so they may be more vulnerable.

I always say, though, that it is a positive addiction-- something that will enhance your life, and stop you from sitting in front of the television and vegeing out.

Of course, it depends what you want from running how much it will take over your life. If you only running for fitness reasons all you need to do is run three times a week. Say, 15 mins twice a week and perhaps a longer run when you have the time. This longer run needn't be that far-- half an hour would do. If you get the bug you can run 5-6 times a week, but keep it under half an hour and you will be fine. It won't be too much, you'll stay in excellent shape, and you will feel great.

If you want to do more, great, but remember to listen to your body. If your knee gives you a little pain (a "niggle"), take care of it and have a rest.

At the moment I'm only running perhaps 3 times a week. Twice at the weekends, and once during the week. On a Sunday I do an hour's run, but during the week it may only be for 15 to 20 minutes. I cycle every morning, though, so this keeps me fit as well.