Grief and joy can co-exist.
I wouldn't have thought so before Olivia because, at least to me, they seem like polar opposites. But I have found, that even on the darkest day, there is joy to be found. At first, it was probably mostly grief with little bits of joy mixed in, but gradually the days have changed to not include so much grief. There is more joy now, with bits of grief scattered here and there.
The two lessons this teaches are these: just because I'm grieving does not mean that I never smile and just because I am smiling does not mean that I never grieve. I think most people probably realize the first to be true. If you've ever been to a funeral where you're remembering the loved one who has passed, and reminiscing about their antics or stubborn streak brings you to laughter, you'll know what I mean. I know that the second lesson might be a little trickier to understand as many people may see the smile and assume that I am 'over it' or that there are no longer tears lurking beneath or that I have moved on. Which isn't exactly true.
It's freeing for me to realize that the two, grief and joy, aren't mutually exclusive. I don't have to choose between them. I can have a sad day with smiles sprinkled in or I can have a great day with a sudden bout of tears.
And it seems that the one makes me truly appreciate the other.