Unfortunately, last Friday I did something weird to my left hamstring -- moved my foot at a funny angle, or something. I had to be careful of it for the rest of that ride.
It didn't seem to bother me on January 1, and yesterday I was able to ride pretty hard for four-minute intervals. Afterwards, though, that hamstring felt pretty sore, and today I knew I'd better stay at an easier pace. I'll try some hard work again tomorrow, and if the muscle acts up I'll have to ease up again. I guess that's part of being a cyclist. Good things happen, and sometimes bad things happen. But just as long as I can ride, that's the main thing.