How do I motivate a teenager?

Actually, no - I wouldn't, runnerman.

If he WANTED to apply to X Factor then that would be fine and I would support him, but I wouldn't try to pursuade him to if he wasn't interested.

There's nothing wrong with encouraging people to do things they WANT to do.  If they don't want to do them, and you keep on about it, then it's just nagging!

I can hear it now, thirty years down the line......  "You want to do xxxx...". 

No, Mum, I don't want to.  If I wanted to, I would.

runnerman.................they need encouragement but they need to find their own motivation...............they can find enough motivation for playstation and face book then they do not lack motivation its just not in the direction that you want it................

therefore encourage

This seems amazingly simple to me.

 Don't go on about it to him, don't "gently encourage him" (with parents theres no such thing, kids see straight through it!), just mention to him, ONCE:

You did really well on that run we went on! If you want to continue running it could help your fitness and speed for football (I sexistly assume he likes/plays football like every other teenage boy I know), it'll help you get a great body AND you might meet some hot girls if you join a running club".

Then LEAVE IT. Covers the most important things to boys

1) Being better than other boys at something

2) Being sexy

3) Hot girls/hot boys (whichever way he's inclined). 

If he still isn't interested, he isn't interested. Accept it! 

Teenagers can be a battlefield. Its a age where they heading towards adulthood and think they know better than you. They start using their month which was normally used for eating.

But as a parent, you want to get the best out of them. Education is important. But if a teenager is
good at a sport or anything else. Why just let them get on with it for which they might give up.
You don`t need to tell a teenager they got to do it. But you can always encourage, motivate and inspire them to continue something which the good at. If teenagers don`t get the motivation and inspiration, they would become nobodies.

whole new can of worms.............

 i spoke to one of our lcoal athletic clubs about a trial training session and they have advised me that 10K is too far given his age - anyone have any views on this

athletic clubs are very different to the running clubs. an athletics club would probably need then to start short and build up getting used to the track.they also like the kids to do a mixture of events like discus , long jump even if they are not interested.........

A running club ignores al the field events and short distances and only does runnning............

The distance depends on how much he has been running in the past......does he take part in school cross country.........if he hasn't done any running then if he does lots of 10 k races and long training runs he risk the same as all of us of doing too much too fast too soon...........

To anyone encouraging their kids to get into running - a word of caution - Both my sister and I were both considered great runners at school age and both joined an athletics club.  We were both pushed really hard and got some great results and plenty of medals HOWEVER - I ended up with osgoodschlatis disease in my knees (attributed by many orthopaedic surgeons to over training while still growing) and could barely walk from the age of 16 to 19.  I was told I'd never run again - happily I started again in my mid 20s and have v slowly worked my way up to a couple of marathons.  I still have hideously disfigured knees though!

My sister fortunately got through it all unscathed - possibly because she was a couple of years older? She had a great degree of success and ran for the england junior squad a couple of times, but then when she left home at 19 she discovered how much of life she felt like she'd missed out on and quit completely and has never run since!

I know these are both extreme cases - but really let youngsters enjoy their running,  get them good training advice and encourage them gently, if it's really for them they'll find their own enthusiasm and motivation!