Playing tennis alone

My masticatory muscle seems to be ok.
Today I enjoyed playing tennis against a wall at a park, where the wall was occupied by lots of kids practicing baseball when I came yesterday and fortunately today they were playing baseball at the another place in the same field.
It was also fun to throw back balls they missed, but I think I'll go there tomorrow morning, at least before noon while kids are in school to make sure I can play enough and not to take children's place to play.
I hope I can continue the good exercise as a new habit.