I've solved plenty of problems when I swim. There's so many different "rooms" and frames of mind I can be in during that activity I think that's the main reason

I've solved plenty of problems when I swim. There's so many different "rooms" and frames of mind I can be in during that activity I think that's the main reason why it doesn't happen as often during weight training. While swimming I can come up with the solution in the shower, in the sauna, while doing my sets in the pool and while resting between sets. I switch between being completely immersed in water, almost deprived of sensory inputs, and being above water constantly.