I've done at least two 40 mile rides this year, then two 60 milers, one around 75 and they all turned out to be much easier than I was expecting. I will do 85 tomorrow, but I'll probably ride to the meeting point so I may actually end up doing a 100 tomorrow. It'll be the most hilly so far too, so I don't know... I've lost some weight around the waist in the last month because of all this riding. So each ride comes a bit easier. I also try to eat well, take my vitamins, drink enough water, all that jazz. So you may consider all that a "training", but that was not my intention. I just want to ride as much as I can and that causes me to become lighter and stronger. But the primary motivation is just to ride. To feel good and have fun.

I commute 16 miles daily too.