Of course there are. I have plenty of them. The most prevalent is "too much wind." Yesterday, Monday, it was difficult walking, let alone riding. So that became stretch and stength day, inside. Sunday I did my regular ride, but even leaving at 6:30am the wind was still strong in my face for the first hour.
Not that it mattered much, because on Sunday my legs took a day off. D'you know how the quads feel at the end of a hard ride? That's how mine were at the start of the day and they never loosened up or gained power. Each time I tried to get serious, they threatened to cramp. Even with the wind at my back I was a couple of gears short.
Ah, but the 42 miles were done and are in the bank.