The tree of life is a kabalistic construct complex enough I don't even begin to understand it, really. There is a very complicated meditation based on the 'proper' tree of life which involves clearing and connecting the 10 points and the paths between them. Perhaps someone who understands this better will node it. But there is another form of grounding, centering, meditation also called the tree of life that is much simpler that I will now attempt to describe.

sit, or stand, but most people don't like standing this long.) Get comfortable. Visualize yourself standing in a beautiful grove of tall stately trees, warm sunlight streaming through the leaves and a cool breeze blowing. Then become a tree in that grove yourself. It's not as hard as it sounds.

Feel your spine straightening, thickening, growing, becoming a tree trunk. Feel energy from the earth rising up through it.

Feel roots growing down deep deep into the earth, from your trunk, your legs, anything touching the ground. Roots growing deep into the love and warmth of the earth herself.

Feel power up through the earth, drawing it in with each breath rising up through you like sap through a tree, bringing energy and warmth and peace in with each breath.

Now feel branches growing up through the top of your head, growing and branching and spreading in all their glory. Feel the branches grow so rich and large and lush that after reaching for the sky they bend gracefully back down to brush the earth with their leaves. (You may physically raise your arms skyward if you wish, but many people find this tiring.)

Now instead of just taking energy in, pull it through your trunk and your leaves and send it back into the earth, a complete and whole circuit. Breathe energy in and up through you, then back down, feeling power go wash through your entire body, cycling through. Continue as long as desired, taking energy in and returning it back, until you feel centered and energized.

Then return to yourself, take a breath in and energy in, then pull up your leaves and branches and pull those back into the crown of your head, and feel the power draining back down your trunk, energy returning, going out through your roots as your branches dissipate. Some people prefer to pull the roots in, then release the trunk, and some prefer to feel the trunk return to flesh, then release the roots. Choose what feels right to you. Relax, breathe deeply, pull yourself back to reality completely again.