When I first started running I was at about a 13 min/mi pace. I lost 40 lbs, ran a whole lot and got faster. I was still only at a 10 min/mi pace. The fastest I ever ran a 5K was 8:24 min/mi and I almost died. I really tried, but couldn't get any faster, so I decided to go back to my 10-11 min/mi and just enjoy it. I'm like you: fast on the swim and bike, but almost dead last in the run. Oh well- I'm NOT twiggy, I'm chunky and round and bubbly, but I have fun and for me that's what it's about.

My DH has been desperately trying to get to 8 min/mi with dedicated, consistent training for years (speed work, strength specific work, coaching) and the fastest he can run any distance (more than 4 miles) is 9 min/mi. I just think some people are cut out for faster running and some are not (I typed fatter running first- oops I guess I know where my mind is when it comes to running and me).