Thank you, corporate!
Thinking of it as 'light seat' really helps.
I think the horse was just having a bad day... The first lesson I had (the one I was referring to before was only the second), he was very responsive and even jumped into the canter a few times when I asked him to trot. His canter- when he feels like doing it- is a dream. This second lesson, the weather was kinda gloomy and I had to convince him to wake up and get up when I got him from his stall. So, I don't know what he'll be like in the third lesson... I'll schedule it for a day with nice weather. :)
I feel funny asking for spurs or a whip, though. I've used whips and crops before, but never spurs, and I don't want to seem like I'm saying 'This isn't working so it's obviously the horse's fault'.
Good luck hppefully it was an off day and it doesn't happen too often. When my horse is having an off day I got do something different. Like I would go jump because barney loves jumping and then I take him out around the fire breaks in 2 point :) wakes him up!