I had a little bit of success with grounding, but you kinda have to be aware you’re zoning out. Look at or touch an item, like observe the crap out of it describing it to yourself for a few seconds and then move on to another after a moment. Doing something engaging enough to hold your focused attention helps, but it’s also hard to motivate yourself to want to zone back in. Basically you got to focus on the outside world and drown out your inner thoughts. You only can really manage to focus inside or outside at once.