A friend of mine shared this on facebook, from a UK based blog called the runningbug:

There are certain things we all say and do that make us certain that we're runners.

Share with your running friends on Facebook and Twitter, and tell us which of the following applies to you.

If you recognise yourself in more than 5 you are definitely a runner!

You know you’re a runner when…

…your shoes have more miles on them than your car

…the first thing you ask the doctor is ‘can I still run?’

…you can spell and pronounce plantar fasciitis

…your feet look like this… 

…you pack more running clothes than casual clothes when you go on holiday

…you’re always hungry

…you get jealous when you drive past runners in a car

…you spend more time researching a new GPS watch than you do a new car

…you know what an illiotibial band is, and where to find it

…all of your usernames have the word ‘run’ or ‘runner’ in them

…the first thing you do when you move to a new area is research running routes

…you get invited to a social event and automatically think about which race it’s going to clash with

…you’re excited to get a foam roller for your birthday

…the phrase ‘It’s all downhill from here’ actually cheers you up

…your  running shoes are the most expensive shoes you own

…you see someone running and try to guess their pace

…your entire birthday wish list can be found in a running store

…when someone asks you your plans for the weekend you respond in miles

…you’re too tired to do housework but manage to go for an hour run

…you get offended when someone says they saw you ‘jogging’

…you have bigger calves than biceps

...guilty of most of these lol

There are a lot of these lists out there, but this is a pretty good one.

Don't think I've seen this item on other lists, but it is spot on:

…you get jealous when you drive past runners in a car

...especially when you're injured.

…you pack more running clothes than casual clothes when you go on holiday

  

…you know what an illiotibial band is, and where to find it

 

…you get invited to a social event and automatically think about which race it’s going to clash with

 

 …the phrase ‘It’s all downhill from here’ actually cheers you up

 

…your  running shoes are the most expensive shoes you own

 

…you see someone running and try to guess their pace

 

…when someone asks you your plans for the weekend you respond in miles

 

…you’re too tired to do housework but manage to go for an hour run

My faves.

Nice list, not what I thought when I opened it.

my feet/toenails haven't looked that good in

14 years.

That foot cannot belong to a runner, what with the lack of calluses and presence of clear, healthy toenails.

Odd, I don't think more than 5-6 of them are applicable to me. 

Beat me, the only one that applies to me is plantar fascists.

You run with a barefoot runner and don't find it odd.

You have seen this topic more than three dozen times.

That too

You don't just eat and drink, you fuel and hydrate.