I wrote this in the other thread, but what worked for me was getting a HRM book and figuring out an organized schedule of training which incorporated hard days, rest days, and strength-building. I found the hardest thing about the schedule was doing the easy rest days because all my friends would ride off ahead, obviously enjoying the opportunity! But after a while, I could drop them even on my easy days. Which is when I started riding with a faster group and the process started all over again.

You can ride for enjoyment or you can ride to train. If you're lucky, you can enjoy the training. I do. My biggest issue is the amount of time I can devote to it. But most people over-estimate how hard they're working, and spend most of their time in the 'dead zone' of training. Which is great if you're cycling for enjoyment, but not so good for improving your speeds.