2 words....DO IT! 

I know exactly what you are feeling.  I turned 48 this week...started running July 7, 2008....ran my first 5K in September....3 other 5K's and a 4 miler since then and have a Duathlon and 2 more 5ks already on the calendar for 2009!  I have been visiting here and learning since day one of my new running life but I believe this is my first post....shows how strongly I feel about encouraging you to GO FOR IT!  You won't be the fastest, you won't be the slowest, you won't be the oldest, biggest, skinniest, tallest, shortest etc, etc, etc.  You'll just be you...doing something that will give you a HIGH for days! 

I, like you, knew that walking was an option in the races but didn't want to...so I didn't.  Just watch your pace, slow a little if you need to, speed up when you can.  Listen to your body.

There are TONS of people on here with MUCH more running experience and knowledge than I have...just wanted to give you a high five and atta girl.  Good luck!

Edit - I stand corrected...this is my 2nd post!   :^{0 :}0

Robin,

You'll be able to do it no problem!  If you realy want to run the whole thing and you think you can't do it, slow down your pace.  My pace can be slowed to a near crawl just so I can say I never stopped running.  I swear when I think I'm done I can still run a 14  min mile and other people walk that fast but in my book I never quit!

think of the really hard things you have done during your life, the big challenges, you thought you could not do at first -  things like graduating from school; giving a speech or presentation in front of alot of people you didnt know; having a baby; taking on a special project at work - and think of the tremendous feeling of accomplishment you had once you met that challenge/goal. 

that is the feeling you will have when you finish that 5K, and that is one of the greatest benefits of running  - you challenge yourself - you look fear in the eye - and you meet and exceed that challenge - and it is very addictive

hold a sock out in front of you and think of that as your current comfort zone.  now stretch that sock really hard and release it, and notice how it doesnt go back to its original shape - i.e. you have stretched your comfort zone - that is what running does to you - it makes you get outside your comfort zone, you build your self confidence -  and move to the next level

yea the first 5K can be a little scary , but you will finish it - and just like the sock you stretched - you will never go back to the old comfort zone - you will have achieved a new plateau and a new measure of self confidence - and you will be so proud you wont be able to talk about anything else for days -  and you will set a new challenge or goal for yourself - and you will start to believe you can accomplish anything

Run your own race. I'm 49 and I train and race running intervals... run 6 minutes then walk 1 minute. I may never "win," but I always finish.

p.s. I've only run for a year. Welcome to a fun addiction.

Robin,

Congratulations on setting a goal to run your first 5K!  The great thing about running, particularly in races is that it is more of an "event"  filled with supportive people cheering you on, including other runners.  When you are out there on the course, just remember why you set this goal in the first place and know that you can do it!! 

Good Luck!

Robin i am slowly approaching 56 and started running about 4 years now. I am not a fast runner but i truly enjoy the sport. You will do fine, when race day comes around and you will be able to relax because everyone is in a good mood. The first race I just wanted to finish and everyone is fully of energy at the finish ,cheering you on. this just made it all worth it. Now I just try to beat my time from the previous year. I did finally get third in a race, i was so excited.

Your will be fine....and good luck....

Joyce