If you are running a 25min 5k and can run 6 miles without too much issue, then I say sign up for the 10k. All depends on what you mean by "ready" to race in the 10k. In other words what your goal is: Just finish? Win? Midpack?
If it wasn't for the fact that my wife competes in triathlons, I'm not sure I'd ever run. However I am her primary training partner so run I do. 10k is our usual training run. Our training for the week alternates run, bike, run, bike, etc. I don't swim so she adds in the swim training and we also try to hit the weights as well. It is amazing how much weight training can improve biking and running. We also go over to the high school track for a speed workout. Run 200's and 400's. Important to do some speed workouts like that so you don't get in a rut with your running.
We are running a 10k this weekend. We usually do a couple of run events each year. I have no goal other than to finish mid-pack. No way my 200lb frame is ever going to compete with the 145lb guys.
Good shoes are paramount. I can't run without some sort of insert in my shoes.
I have no desire to do anything more than a 10k though. A lot of people who start running have the goal to eventually do a half or full marathon. I have no such desire.
I greatly prefer bicycling. Far less impact on the body and you get to obsess over bicycles and parts just like motorcycles. I just bought a new Litespeed Archon C3. My interest is in bicycle racing.
My wife is into tri's but I don't swim. I greatly prefer bikes. So as kind of a middle ground we do 3 "duathlons" every year. Typically: 3mi run, 14-18mi bike, and 3mi run. Sometimes the run distances vary depending on event. If you have a bicycle (any ol' bike) and want a unique challege try a duathlon. It is just like a 10k only interrupted in the middle by a 14mile bike race. Joe
2002 VFR 800
1999 Vulcan Nomad