Don't cancel on yourself.
You have an important meeting with a big client.. a doctor appointment.. or an interview for an amazing job. Whatever it is, this appointment is important. You put it in to your calendar so that you don't forget about it. You are ensuring that nothing else gets in the way.
Well, here's a little tip for you - treat your workouts the same way! By scheduling your workouts (at home or at the gym) you are placing importance on that "you-time". By pencilling it in to your schedule you are saying "I am important. Taking care of myself is important and nothing will get in the way".