You can hug a tree at any time

Time and again meditation is also scientifically proven to be both a preventer of heart disease, cancer, anxiety, hypertension and a host of other ills, as well as a healer of those ills.

We in the USA have lost touch with our connection to the Planet.  Even as late as the 1930s we had 35% of our population living on farms, most without either electricity of running water.  I remember as late as 1950 working on a farm that had neither of those - if you wanted water you went to the kitchen sink and pumped, real indoor plumbing.  If you wanted to poop you went to the outhouse and not many years before that even those were a rarity.  

Trees are living entities and are grounded in the soil.  When you are near one it assists you in your own personal grounding as well.  You can be grounded and "earthing" sitting in your living room - you do not have to be next to a tree though that is a great experience at times too.  An earthing mat is utter bull shit - you don't need one, all you need to do is to be grounded and connected with the Planet and running your own Earth energies through the channels that carry that flow.  Learn to be grounded from your first chakra to the center of the Planet, run your Earth energy, and you can do that 24/7 - even while on the Astral.  You can be grounded and running your Earth energy at 40,000 feet in an airliner, balloon, or rocket ship and be grounded every bit as well as while hugging a tree.

We have have lost what our ancestors knew while they lived even without shelter.  The bushmen of the Serengeti have no words for either yesterday or tomorrow.  Everything with them is now.  (Science is still going nuts trying to define time and they haven't done it yet - it doesn't exist, there is only now.)  The "primitive" people also aware of the many spirits who are here to help us.  The Australian aborigines are aware of the Rainbow Serpent which everyone of us has within us - our kundalini energy.  By practicing a grounded and Earth energy meditation one will discover their chakras and that kundalini which runs up the spine of everyone.  But must people would rather believe they are just a body and try to heal the body when it is spiritual ills that are causing our physical problems.  Today we're just too damned smart for our own good, both allopathic and alternative, or so we think.