Is it reasonable that I don't want to go to softball?

It's just an essment practice, and we've already had 2. I didn't go last time, it was canceled because of rain. My parents told me i had to get exercise (no im not fat or out of shape, i am one of the fittest in my cl and can run an 8 min mile and im not even a runner at all, its just cause i wasn't currently in a sport). I REALLY don't want to go cause I hate softball and tonight is the most boring night of the season, no exaggeration. How can I tell them that I don't want to go? And NO Im not going to lie to them. I realize that I could just tell them but I've tried that once before on basketball and it SO didn't work, they were just like "i don't care, you still have to go". And yes, I will be going next week, no question about it.