What should I do as cross-training for running? (more details below)?

I’m a sophomore in high school. I ran winter and spring track freshman year. I didn’t do cross country (long story), but I’ve been training since the beginning of August.

Winter track started Monday.
My left leg is okay, but I have a shin splint and strained hamstring in my right leg. I know what to do for my shin splint and hamstring, but the athletic trainer said I should cross-train over the weekend.

I know swimming and biking are really common cross-training activities for running. I can’t ride a bike. I might be able to get to an indoor pool, but if I can’t get to a pool, what should I do tomorrow as cross-training?