Way of Nature is a good choice I think. Of course, doing things in nature also helps, like sitting against a tree relaxing, or walking/working barefoot in the garden.
Most of it comes down to the mindfulness principle of checking in with your body. Whatever you’re doing, see if you can describe what your body is feeling. If you’re standing, try to really describe how the floor feels on the soles of your feet. Is it warm, cold, soft, hard, comfortable or uncomfortable.
Paying attention to your breathing also helps, mentally following the breath as it goes in and out, slowing the out-breath down, doing ocean breath (ujjayi in yoga).
If your attention is on what’s happening in/to your body, it can not be anywhere but on the ground and in the present. With practice it becomes easier over time until you start noticing textures of everything you sit on, walk on or just touch. And you can feel which of you nostrils is dominant (your nose switches between them every 45 minutes or so).
Qigong has lots of grounding exercises as well, also exercises to deal with the shifts which happen during the change of seasons which can make people depressed or hyperactive.
And in the meditation department, simply imagining a tree or mountain, trying to imagine the part below the surface as well. Trees and mountains are often seen as representations of the ground. Or touching a tree and considering how many years that tree has been growing to be there at that size, how much effort and energy it has taken.
If you’re into crystals, Hematite or black Tourmaline are known to be very grounding and usually not that expensive.
Ravenscout’s advice is interesting, I’m one of those people which rarely eat meat, vegetables are king in my diet. But I do eat slow, aware of how the plant came to be, which automatically tunes me in to the earth. I also make my own mineral water with mineral stones from deep, deep underground.
Basically my challenge is opposite from yours, I generally get “stuck” in my body and my habits. Like an Ent, slow to change.