how can you play byeyourself

[fanboy1234]

how can you play by your self

[Rob ITST]

A wall, a ball machine, practice serves.... I've even tossed the ball up in the air and hit groundstokes.

There's actually a really good overhead drill you can do against a wall:
Hit a serve that hits the ground just before the wall (about 1-2 feet) and the ball will fly up in the air so you can smash it - hit an overhead back to the same spot - repeat.

[Corbon]

Good old wall tennis. Poor old garage doors.