My son wants to play sports, any sport, all the time. His sister would be a perfect opponent, except for a crippling lack of interest in any sport at any time (except for boxing – an interest I strongly encourage because one day she will be fifteen.)
After breakfast, my son invented pajama dodge. That is they throw their pajamas at each other. This is the kind of sport GoofGirl can go for, at least for a while. She enjoyed the novelty of throwing her clothes around. But my son really wanted orderly tournament level play.
GoofBoy is also a wonderful big brother (most of the time) and he has been known to give his sister massages (yes he will undoubtedly make some girl happy in a decade or so – assuming I let him live that long.)
So he gave his sister an incentive to really play, offering her massages when she wins. It worked. GoofGirl focused and bore down. Grunting as she hurled balled up pajama bottoms and tops at her brother. Her brother, though older, stronger, faster, and more experienced was cornered. He tried to counter with psychological warfare (trash-talking.) But his sister was nonplussed, yelling, “I’m just doing it for my massage.”
After a bit more battering GoofBoy conceded and paid up. As he worked on her back and feet (kindergarten is pretty stressful) she smiled and sighed. My son smiled too, he wanted a worthy opponent and he created one.