This is one of my favourite go-to grounding exercises. We can always count on the following: our feet (or other parts of us) on the ground, our breath, and our own ability to expand and grow (literally and metaphorically). Try this for 3-5 breaths for each step!
Mindful tip - it helps to start practicing any mindfulness exercise when you're calm, then eventually applying it to more stressful/difficult situations.
