Hold your hand against the furrowed trunk of an old oak tree, brush a feather against your skin or walk barefoot through a meadow.
Clichés, yes, but these things really do have a way of making you feel more grounded.
Try repotting a plant.
Remove it from its container and gently agitate the soil around the roots – is it cold? What do the roots feel like between your fingers? Place the plant into a larger pot then top it up with soil, patting down the surface around the stem to hold it in place. Water well, feeling the liquid on your hands.
Almost without realising it, those few minutes of mindful contact with nature will have reduced your heart rate, easing feelings of anxiety, frustration and even anger.