I think the word for this is "equanimity" and it is certainly a desirable state. But it should not be "grey" like the sibling comment indicates but full of joy

I think the word for this is "equanimity" and it is certainly a desirable state. But it should not be "grey" like the sibling comment indicates but full of joy, bliss and wonder. I think experiencing equanimity is a sign of releasing the ego which is natural as we age and become less attached to our ideas of who we are and closer to the reality of our impending death