You've gotten a lot of good advice here -- and advice that I am soaking in like a sponge - because I really think I could have written your post!
I am a cyclist who recently took up running (okay, okay..."JOGGING"
). I can ride my bike for 100 miles and feel better at the end of it than after a 3 mile jog around my neighborhood. Jogging/running is a brutal sport, I'm discovering. Everyone told me..."Oh, you're in such good shape from all that cycling you do, running will be a breeze!" But, as I'm finding out as many here have - that it's a different animal entirely. I suffer. I am not a runner. Okay...I knew that, I just refuse to believe it. I just keep trying and maybe someday, I'll have that Zen moment that runners talk about.
2007 Seven ID8 - Bontrager InForm
2003 Klein Palomino - Terry Firefly (?)
2010 Seven Cafe Racer - Bontrager InForm
2008 Cervelo P2C - Adamo Prologue Saddle