To be fair, that is kind of how saiyan biology works: being beaten the shit out of and still still surviving = massive power boost. Or it could be a fault of toriyama's writing

It's more like the heat of battle is getting his blood pumping and ready to take things seriously. It's why he starts out as a base super saiyan and works his way up to god as it progresses.

Plus, we all know Goku is masochistic as fuck, this is everything he needs. Can't wait for the next episode where Kafla stomps on his balls some to really get him motivated.