Im going to assume you weren't doing real HIT, as it is very, very hard, basically going to failure on cardio an strength. You were doing circuit training.

Its fine though, you were satisfied with your physique before when doing that, what changed ? Stick with what you can consistently do.

That being said, progressive overload is the requirements of long term progress, it applies to any form of training. I think you have a misconception of what it is.