How can it get even better?

[xise]

Gratitude is an emotion, a feeling of happiness-thankfulness.

Control is a desire to have a certain thing in reality and rejecting other configurations.

You can desire/want gratitude, but as long as you are open to sadness or whatever other emotion that comes, there is no control. Rejectance/control is basically about extreme emotional dislike of certain situations/states of the World plus an overwhelming need to take action to avoid the dislike. Acceptance is basically being at peace with all situations and states of the World, and is also compatible with gentle action where you are not attached to see that action having any effect or outcome.

With respect to how to actually feel gratitude naturally, once again, it's related to inner self-work and removing fears and embracing level, as opposed to purely repetition, though repetition can help if it alongside substantial inner work. Many of the new age spiritual memes are dangerously close to spiritual bypassing; maybe of these wonderful feeling emotions arise naturally through inner self work, not primarily through reminding ourselves to be happy. 

Happiness arises organically from inner work, not the repetition of a one-liner.