Everyone who dances knows that day. You wake up, you have no energy, and the last thing you want to do is train. I used to think it was a motivation problem — that I wasn't determined enough. Now I know it's normal. And I also know how to handle it.
Motivation is a feeling. Feelings change. Consistency is a decision. Decisions can be made regardless of how you feel.
My first tool is the minimum dose. On a hard day, you don't have to do a full training session. Tell yourself: "I'll do 15 minutes and see." Why 15 minutes? Because the resistance to starting is always greater than the resistance to continuing. Once you've started, you often end up training for an hour.
My second tool is a schedule. I have fixed training days and times. I don't think every day about whether to practice — I simply know that on Tuesday at 4pm I'm in the studio. That eliminates the decision and reduces the chance I'll find an excuse.
Third: understand what you need on a given day. A tired body needs different training than a body full of energy. I've learned that you can train consistently without always training at full intensity. Stretching, slow technique work, listening to music and improvising — that's training too.
Also remember why you started. When I don't feel like training, I think about that feeling when I hit the beat perfectly. About how I feel after a good freestyle. That reminds me that dance is the answer, not the question.