For me it’s getting the mindset right before the ride. If I’m doing a training ride, the preparation is all part of the ride and that includes the mental focus of what I will be doing that ride.
When I’m out on a training ride, that is the focus. My mind concentrates on the ride and me doing what I should be on that ride.
When I know I’m doing a bimble, and that’s quite regular, even during the prep I’m doing it at a slower pace. I’m not thinking about what I need to do, just thinking of how I’m going to enjoy it. I pick routes I do less often, I also don’t take a computer. See a path or a track you want to explore, go for it, might go nowhere might open up a different route. I don’t want to see I’m doing x watts or x mph. I purposefully sit more upright on the bike. Spend time looking around, observing what is happening, enjoy the fact that I can stop at a bench etc. If I see something to watch I will do so.
When I first stopped racing it was incredibly difficult to slow down. I was exactly the same OP. But empty your head of the concept of speed and racing, and be in the moment more (if that makes sense). I love bimbling now, I go out with my missus quite a lot and my primary concern is ensuring she enjoys it as much as I do.
Ultimately though, do what you enjoy. If you’re not ready to bimble, don’t. I strongly recommend you do as I find it really calming, but hope I’m not sounding preachy!