How to tell my mom I want to quiet cross country?

I was on my cross country team last year and was The worst person on the team. Well there were only like 5 girl but I would come like 5 places away from last place agaist other schools. I never had a problem with xc but I never really had a passion for it. I don't really know if I want to quiet yet (i'm still trying to deciede) but I want to let my mom know I'm thinking about it. I play softball and am really passionate about it. I'm not even one of the best but I still really enjoy it while xc I feel like I just do to do it. This year most of the girls team is leaving (they were seniors) and were getting a bunch of freshman. I know a least three other girls are joining (other than the fishys) it will be this jr Alex who i never talk to, this girl Tiffany who Always hangs out with the guys and my NFC Andrea. Last year Andrea couldn't go to some of the meets becuase she had bad grades and I don't want it to be the same! Because when she was there I felt comfortable about being near last because she told me at least I finished! and when she wasn't there I felt like everyone was staring and thinking I was sooo slow. I wouldn't mind staying in xc because it's a good way to exersize (yet the workouts can be harsh) and Andrea might be there with ne but on the other hand I come in last and if she's not there I feel bad about being bad. So I have two questions! Should or should I not quit? And I don't want any "well it's your own choose" I know that but I want to hear others points! And how should I tell my mom i'm thinking about quiting! You don't have to answer both and sorry for bad spelling