No laughing, blueberry! Running is not easy -- to me it's much harder than cycling. I know there are people who are natural runners (like my husband), but it is difficult for me. Every quarter mile early on was a struggle and an accomplishment. All the books say to do walk/running for quite awhile before graduating to all running. It takes times for your joints, tendons, ligaments, etc. to adjust. It *does* get easier, but at least for me, not *that* much easier! Probably because as you get better, you either push yourself to go faster or longer (or both), so you kinda end up at the same effort level most of the time, or at least I do. 
I did a nice beach run here this am that DH estimates was in the 3.2 to 3.4 mile range. It was very humid after early morning rain, and the sun was coming out on the way back, so it was definitely a challenge for me, but at least my body didn't hurt. Here, I mostly struggle with the heat and humidity, but the temps should be cooling down a bit as time goes on. It's already better than when we got here in late August.
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