That equation is based on Einstein's Theory of Relativity.
These mermaid sisters remind of this theory. My energy is relative to where and who I am with.
When I looked at this card it also reminded me of children at play. Who has not thought 'I wish I could bottle some of the energy those children have, and use it for my own.' I think some of that youthful energy is the fact that children are not yet bogged down of all the drama of day to day life. Given that, this meditation card reminds to set sometime aside for play time; to disengage of the drama for a bit and connect with my inner child.
And going to the beach is always a plus.