There has to be enough motivation to go That's all that is required. We cannot know what might happen when we're there based on what we are thinking before we go (in another place in the distant universe of our head :-)

If it is raining, do you decide not to go outside ever again because you don't feel like getting wet?

Yes sometimes one does decide to snuggle up in bed with a good book and let the world pass until the sun comes out again but most times one goes to work and continues one's normal schedule, getting damp and a bit downcast with the overcast, gray skies and dreariness of it all but confident too that it's mostly just an illusion; what we're actually doing in our life/at work, school, home, etc. and the weather are not really related.

It's similar with feelings and actions. The feelings inform us about ourselves or the world around us. When we're feeling unmotivated or sad or raining on ourselves, we need to note that and look for our umbrella and wear brighter clothing, remember to smile more often and focus on things we are doing in our lives (going to therapy). On any given day, work or therapy might not have earth shattering fun and exciting happenings going on, but the filing has to be done as well as the work on the big project that might get you a raise. It's all worthwhile, despite how it makes you feel, the feelings are there to help you adjust, not to get in your way.

I often would feel overwhelmed and lose motivation for awhile in therapy and that's when I would take note and be extra kind to myself but still go to therapy, knowing the "overwhelming" meant I was doing good, exciting work but that it was just a bit beyond me yet, too new or advanced and the loss of motivation was a defense.

Yay, Defense! Remember, you're on your own side! Relax into knowing you can and ARE taking care of yourself, whatever you are doing. Keep showing up. 80% of life is showing up (Woody Allen quote).