To run or not to run!

ok.. so there's this co-worker of mine, who I thought was really stuck up cause she's absolutely skinny etc etc.. embarassed  Yesterday at the lunch table we actually had a conversation about fitness and I couldn't believe that she is obsessive about maintaining her size cause she says she was a bit bigger and doesn't want to go back there. I realised that we had pretty much the same sort of issues. We has a pretty decent dialogue... Lo and behold she sends me an email today inviting me (along with two or three others) to join her in a 5K that's coming up on the 23rd of this month! I have never thought of doing a 5K before and wow!! I don't know if I should or not! I mean, I never really ran before.  My question is... should I or shouldn't I run the 5K.. I have until Friday morning to decide!