If you want to express emotions, why do you reach for sadness first? Or do you want to show the arc that leads to happiness, to a happy ending? Because uplifting feelings have to start from the bottom. Could it be any other way?
Dramatic stories usually start with an upward arc, from everyday life, where the viewer is currently located. Something has to happen from this position. Obviously, the mood has to shift downward, then upward, and possibly repeat several times along the timeline. The ending can be climactic, euphoric, happy, or suddenly subdued, tragic, and painful.
Does the film definitely need a story, or is it enough to depict the mood? Is an internal story, which is really just a play of thoughts, enough? If there is a connection, a development, and not just a list, then it will be the story of the transformation itself.
Emotions should not be documented, but induced.