VeganBikeChick,
You've only been running a month and already ran a 5K? You have nothing to feel bad about! That's really quick to get up to that distance. Don't think you can do it again? Well, just scale back a bit, do the run/walk thing until it comes. Yes, it is mind over matter to some degree, but it also takes a body time to build strength and endurance used for running, which are not the same as for cycling. It's not just about aerobic capacity.
I am only running a 5K distance even now, and I've been "running"/jogging, whatever, for over 2 years, so you have nothing to feel bad about. Depending on the weather, my mood, and how much exercise I've been getting (or not getting), sometimes even that 5K distance can feel like a marathon, and I have to play mind games to get myself to the end, like imagining that my deceased father is waiting there for me at the end.
All that said, I did my 5K beach run this morning for the first time since I wrenched my back 1.5 weeks ago, and it felt just fine. However, klutz that I am, I tripped on a root on the path and fell, skidding with both palms on the sand, which was a bit of an owie, but I didn't see to do any other damage and was able to finish just fine.
Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow