Taylor Swift likes her workouts solo -- as in she doesn't just book a trainer, she books a gym -- sorry Justin Bieber.
Here's the deal ... Justin was at Dogpound Gym in West Hollywood with a bunch of people, but then Taylor and her crew rolled up.
We're told everyone -- including JB was asked to get the heck out of the gym -- because Taylor had an appointment. Justin's security team was approached and asked to leave, but JB's team held firm and said he was going to finish his workout before taking off.