Try and avoid the slippery slope of missing workouts and rather go along to the gym with this in mind, "I am going to just enjoy myself today".
If you workout first thing in the morning, then you guys need to get out of bed ON the ALARM. Keep telling yourself that it doesn't matter how you feel now, and that you will wake up, so you need to KEEP MOVING FORWARD.
It will feel great when you do eventually PERK UP; then NOTHING CAN STOP YOU getting out of the front door.
“All the while you are getting ready to go to the gym and while you are there, be your own cheerleader by telling yourself that training is great for you; and you are doing really well as you progress rep by rep.”
"If you train alone, then switch up your workout to fun movements that may not be so challenging but still get the job done. If you are in a class, let the coach know how you feel, then modify the class moves to suit you. Who knows, you might suddenly come alive and really go for it!