In contemplating equanimity I use the phrase 'not asking for anything.' For me the practice of equanimity lies in not asking for things to be any other way than they are, rather to be able to rest with things just as they are. With upekkha, though we wish well-being, we don't demand that things be well; we understand Dhamma. This helps with metta. It keeps us grounded. It prevents metta from sweeping us away.
It's as if you come upon someone you love sleeping. When people are sleeping, their beauty is usually revealed, and there's a feeling of just wanting to hold there in that moment forever. But if you notice the movement of breath in the throat, you can see that to hold still for ever would be death, because movement, the movement of breath, is life. So the impermanence of things is also their life, their flow and their beauty. Upekkha gives us the strength to hold steady with things, and the strength to let go.
~ The Divine Abidings, Excerpts of a talk given by Ajahn Thaniya at the Insight Meditation Centre, Barre, Massachusetts, in April 1996.
May this be of benefit.